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ca6c080eef42e4149110f79cf73a48a6ec4e965d
5942 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Linus Torvalds
|
120a201bd2 |
Merge tag 'hardening-v6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardening updates from Kees Cook: - Introduce the param_unknown_fn type and other clean ups (Andy Shevchenko) - Various __counted_by annotations (Christophe JAILLET, Gustavo A. R. Silva, Kees Cook) - Add KFENCE test to LKDTM (Stephen Boyd) - Various strncpy() refactorings (Justin Stitt) - Fix qnx4 to avoid writing into the smaller of two overlapping buffers - Various strlcpy() refactorings * tag 'hardening-v6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: qnx4: Use get_directory_fname() in qnx4_match() qnx4: Extract dir entry filename processing into helper atags_proc: Add __counted_by for struct buffer and use struct_size() tracing/uprobe: Replace strlcpy() with strscpy() params: Fix multi-line comment style params: Sort headers params: Use size_add() for kmalloc() params: Do not go over the limit when getting the string length params: Introduce the param_unknown_fn type lkdtm: Add kfence read after free crash type nvme-fc: replace deprecated strncpy with strscpy nvdimm/btt: replace deprecated strncpy with strscpy nvme-fabrics: replace deprecated strncpy with strscpy drm/modes: replace deprecated strncpy with strscpy_pad afs: Add __counted_by for struct afs_acl and use struct_size() VMCI: Annotate struct vmci_handle_arr with __counted_by i40e: Annotate struct i40e_qvlist_info with __counted_by HID: uhid: replace deprecated strncpy with strscpy samples: Replace strlcpy() with strscpy() SUNRPC: Replace strlcpy() with strscpy() |
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Linus Torvalds
|
5db8752c3b |
Merge tag 'vfs-6.8.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs iov_iter cleanups from Christian Brauner: "This contains a minor cleanup. The patches drop an unused argument from import_single_range() allowing to replace import_single_range() with import_ubuf() and dropping import_single_range() completely" * tag 'vfs-6.8.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: iov_iter: replace import_single_range() with import_ubuf() iov_iter: remove unused 'iov' argument from import_single_range() |
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Linus Torvalds
|
453f5db061 |
Merge tag 'trace-v6.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt: - Fix readers that are blocked on the ring buffer when buffer_percent is 100%. They are supposed to wake up when the buffer is full, but because the sub-buffer that the writer is on is never considered "dirty" in the calculation, dirty pages will never equal nr_pages. Add +1 to the dirty count in order to count for the sub-buffer that the writer is on. - When a reader is blocked on the "snapshot_raw" file, it is to be woken up when a snapshot is done and be able to read the snapshot buffer. But because the snapshot swaps the buffers (the main one with the snapshot one), and the snapshot reader is waiting on the old snapshot buffer, it was not woken up (because it is now on the main buffer after the swap). Worse yet, when it reads the buffer after a snapshot, it's not reading the snapshot buffer, it's reading the live active main buffer. Fix this by forcing a wakeup of all readers on the snapshot buffer when a new snapshot happens, and then update the buffer that the reader is reading to be back on the snapshot buffer. - Fix the modification of the direct_function hash. There was a race when new functions were added to the direct_function hash as when it moved function entries from the old hash to the new one, a direct function trace could be hit and not see its entry. This is fixed by allocating the new hash, copy all the old entries onto it as well as the new entries, and then use rcu_assign_pointer() to update the new direct_function hash with it. This also fixes a memory leak in that code. - Fix eventfs ownership * tag 'trace-v6.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ftrace: Fix modification of direct_function hash while in use tracing: Fix blocked reader of snapshot buffer ring-buffer: Fix wake ups when buffer_percent is set to 100 eventfs: Fix file and directory uid and gid ownership |
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Steven Rostedt (Google)
|
d05cb47066 |
ftrace: Fix modification of direct_function hash while in use
Masami Hiramatsu reported a memory leak in register_ftrace_direct() where
if the number of new entries are added is large enough to cause two
allocations in the loop:
for (i = 0; i < size; i++) {
hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
new = ftrace_add_rec_direct(entry->ip, addr, &free_hash);
if (!new)
goto out_remove;
entry->direct = addr;
}
}
Where ftrace_add_rec_direct() has:
if (ftrace_hash_empty(direct_functions) ||
direct_functions->count > 2 * (1 << direct_functions->size_bits)) {
struct ftrace_hash *new_hash;
int size = ftrace_hash_empty(direct_functions) ? 0 :
direct_functions->count + 1;
if (size < 32)
size = 32;
new_hash = dup_hash(direct_functions, size);
if (!new_hash)
return NULL;
*free_hash = direct_functions;
direct_functions = new_hash;
}
The "*free_hash = direct_functions;" can happen twice, losing the previous
allocation of direct_functions.
But this also exposed a more serious bug.
The modification of direct_functions above is not safe. As
direct_functions can be referenced at any time to find what direct caller
it should call, the time between:
new_hash = dup_hash(direct_functions, size);
and
direct_functions = new_hash;
can have a race with another CPU (or even this one if it gets interrupted),
and the entries being moved to the new hash are not referenced.
That's because the "dup_hash()" is really misnamed and is really a
"move_hash()". It moves the entries from the old hash to the new one.
Now even if that was changed, this code is not proper as direct_functions
should not be updated until the end. That is the best way to handle
function reference changes, and is the way other parts of ftrace handles
this.
The following is done:
1. Change add_hash_entry() to return the entry it created and inserted
into the hash, and not just return success or not.
2. Replace ftrace_add_rec_direct() with add_hash_entry(), and remove
the former.
3. Allocate a "new_hash" at the start that is made for holding both the
new hash entries as well as the existing entries in direct_functions.
4. Copy (not move) the direct_function entries over to the new_hash.
5. Copy the entries of the added hash to the new_hash.
6. If everything succeeds, then use rcu_pointer_assign() to update the
direct_functions with the new_hash.
This simplifies the code and fixes both the memory leak as well as the
race condition mentioned above.
Link: https://lore.kernel.org/all/170368070504.42064.8960569647118388081.stgit@devnote2/
Link: https://lore.kernel.org/linux-trace-kernel/20231229115134.08dd5174@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes:
|
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Steven Rostedt (Google)
|
39a7dc23a1 |
tracing: Fix blocked reader of snapshot buffer
If an application blocks on the snapshot or snapshot_raw files, expecting
to be woken up when a snapshot occurs, it will not happen. Or it may
happen with an unexpected result.
That result is that the application will be reading the main buffer
instead of the snapshot buffer. That is because when the snapshot occurs,
the main and snapshot buffers are swapped. But the reader has a descriptor
still pointing to the buffer that it originally connected to.
This is fine for the main buffer readers, as they may be blocked waiting
for a watermark to be hit, and when a snapshot occurs, the data that the
main readers want is now on the snapshot buffer.
But for waiters of the snapshot buffer, they are waiting for an event to
occur that will trigger the snapshot and they can then consume it quickly
to save the snapshot before the next snapshot occurs. But to do this, they
need to read the new snapshot buffer, not the old one that is now
receiving new data.
Also, it does not make sense to have a watermark "buffer_percent" on the
snapshot buffer, as the snapshot buffer is static and does not receive new
data except all at once.
Link: https://lore.kernel.org/linux-trace-kernel/20231228095149.77f5b45d@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes:
|
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Steven Rostedt (Google)
|
623b1f896f |
ring-buffer: Fix wake ups when buffer_percent is set to 100
The tracefs file "buffer_percent" is to allow user space to set a
water-mark on how much of the tracing ring buffer needs to be filled in
order to wake up a blocked reader.
0 - is to wait until any data is in the buffer
1 - is to wait for 1% of the sub buffers to be filled
50 - would be half of the sub buffers are filled with data
100 - is not to wake the waiter until the ring buffer is completely full
Unfortunately the test for being full was:
dirty = ring_buffer_nr_dirty_pages(buffer, cpu);
return (dirty * 100) > (full * nr_pages);
Where "full" is the value for "buffer_percent".
There is two issues with the above when full == 100.
1. dirty * 100 > 100 * nr_pages will never be true
That is, the above is basically saying that if the user sets
buffer_percent to 100, more pages need to be dirty than exist in the
ring buffer!
2. The page that the writer is on is never considered dirty, as dirty
pages are only those that are full. When the writer goes to a new
sub-buffer, it clears the contents of that sub-buffer.
That is, even if the check was ">=" it would still not be equal as the
most pages that can be considered "dirty" is nr_pages - 1.
To fix this, add one to dirty and use ">=" in the compare.
Link: https://lore.kernel.org/linux-trace-kernel/20231226125902.4a057f1d@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes:
|
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Linus Torvalds
|
13b734465a |
Merge tag 'trace-v6.7-rc6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt: - Fix another kerneldoc warning - Fix eventfs files to inherit the ownership of its parent directory. The dynamic creation of dentries in eventfs did not take into account if the tracefs file system was mounted with a gid/uid, and would still default to the gid/uid of root. This is a regression. - Fix warning when synthetic event testing is enabled along with startup event tracing testing is enabled * tag 'trace-v6.7-rc6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing / synthetic: Disable events after testing in synth_event_gen_test_init() eventfs: Have event files and directories default to parent uid and gid tracing/synthetic: fix kernel-doc warnings |
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Steven Rostedt (Google)
|
88b30c7f5d |
tracing / synthetic: Disable events after testing in synth_event_gen_test_init()
The synth_event_gen_test module can be built in, if someone wants to run
the tests at boot up and not have to load them.
The synth_event_gen_test_init() function creates and enables the synthetic
events and runs its tests.
The synth_event_gen_test_exit() disables the events it created and
destroys the events.
If the module is builtin, the events are never disabled. The issue is, the
events should be disable after the tests are run. This could be an issue
if the rest of the boot up tests are enabled, as they expect the events to
be in a known state before testing. That known state happens to be
disabled.
When CONFIG_SYNTH_EVENT_GEN_TEST=y and CONFIG_EVENT_TRACE_STARTUP_TEST=y
a warning will trigger:
Running tests on trace events:
Testing event create_synth_test:
Enabled event during self test!
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1 at kernel/trace/trace_events.c:4150 event_trace_self_tests+0x1c2/0x480
Modules linked in:
CPU: 2 PID: 1 Comm: swapper/0 Not tainted 6.7.0-rc2-test-00031-gb803d7c664d5-dirty #276
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:event_trace_self_tests+0x1c2/0x480
Code: bb e8 a2 ab 5d fc 48 8d 7b 48 e8 f9 3d 99 fc 48 8b 73 48 40 f6 c6 01 0f 84 d6 fe ff ff 48 c7 c7 20 b6 ad bb e8 7f ab 5d fc 90 <0f> 0b 90 48 89 df e8 d3 3d 99 fc 48 8b 1b 4c 39 f3 0f 85 2c ff ff
RSP: 0000:ffffc9000001fdc0 EFLAGS: 00010246
RAX: 0000000000000029 RBX: ffff88810399ca80 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffffb9f19478 RDI: ffff88823c734e64
RBP: ffff88810399f300 R08: 0000000000000000 R09: fffffbfff79eb32a
R10: ffffffffbcf59957 R11: 0000000000000001 R12: ffff888104068090
R13: ffffffffbc89f0a0 R14: ffffffffbc8a0f08 R15: 0000000000000078
FS: 0000000000000000(0000) GS:ffff88823c700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001f6282001 CR4: 0000000000170ef0
Call Trace:
<TASK>
? __warn+0xa5/0x200
? event_trace_self_tests+0x1c2/0x480
? report_bug+0x1f6/0x220
? handle_bug+0x6f/0x90
? exc_invalid_op+0x17/0x50
? asm_exc_invalid_op+0x1a/0x20
? tracer_preempt_on+0x78/0x1c0
? event_trace_self_tests+0x1c2/0x480
? __pfx_event_trace_self_tests_init+0x10/0x10
event_trace_self_tests_init+0x27/0xe0
do_one_initcall+0xd6/0x3c0
? __pfx_do_one_initcall+0x10/0x10
? kasan_set_track+0x25/0x30
? rcu_is_watching+0x38/0x60
kernel_init_freeable+0x324/0x450
? __pfx_kernel_init+0x10/0x10
kernel_init+0x1f/0x1e0
? _raw_spin_unlock_irq+0x33/0x50
ret_from_fork+0x34/0x60
? __pfx_kernel_init+0x10/0x10
ret_from_fork_asm+0x1b/0x30
</TASK>
This is because the synth_event_gen_test_init() left the synthetic events
that it created enabled. By having it disable them after testing, the
other selftests will run fine.
Link: https://lore.kernel.org/linux-trace-kernel/20231220111525.2f0f49b0@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes:
|
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Randy Dunlap
|
7beb82b7d5 |
tracing/synthetic: fix kernel-doc warnings
scripts/kernel-doc warns about using @args: for variadic arguments to functions. Documentation/doc-guide/kernel-doc.rst says that this should be written as @...: instead, so update the source code to match that, preventing the warnings. trace_events_synth.c:1165: warning: Excess function parameter 'args' description in '__synth_event_gen_cmd_start' trace_events_synth.c:1714: warning: Excess function parameter 'args' description in 'synth_event_trace' Link: https://lore.kernel.org/linux-trace-kernel/20231220061226.30962-1-rdunlap@infradead.org Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Fixes: |
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Linus Torvalds
|
55cb5f4368 |
Merge tag 'trace-v6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fix from Steven Rostedt:
"While working on the ring buffer, I found one more bug with the
timestamp code, and the fix for this removed the need for the final
64-bit cmpxchg!
The ring buffer events hold a "delta" from the previous event. If it
is determined that the delta can not be calculated, it falls back to
adding an absolute timestamp value. The way to know if the delta can
be used is via two stored timestamps in the per-cpu buffer meta data:
before_stamp and write_stamp
The before_stamp is written by every event before it tries to allocate
its space on the ring buffer. The write_stamp is written after it
allocates its space and knows that nothing came in after it read the
previous before_stamp and write_stamp and the two matched.
A previous fix
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Steven Rostedt (Google)
|
b803d7c664 |
ring-buffer: Fix slowpath of interrupted event
To synchronize the timestamps with the ring buffer reservation, there are
two timestamps that are saved in the buffer meta data.
1. before_stamp
2. write_stamp
When the two are equal, the write_stamp is considered valid, as in, it may
be used to calculate the delta of the next event as the write_stamp is the
timestamp of the previous reserved event on the buffer.
This is done by the following:
/*A*/ w = current position on the ring buffer
before = before_stamp
after = write_stamp
ts = read current timestamp
if (before != after) {
write_stamp is not valid, force adding an absolute
timestamp.
}
/*B*/ before_stamp = ts
/*C*/ write = local_add_return(event length, position on ring buffer)
if (w == write - event length) {
/* Nothing interrupted between A and C */
/*E*/ write_stamp = ts;
delta = ts - after
/*
* If nothing interrupted again,
* before_stamp == write_stamp and write_stamp
* can be used to calculate the delta for
* events that come in after this one.
*/
} else {
/*
* The slow path!
* Was interrupted between A and C.
*/
This is the place that there's a bug. We currently have:
after = write_stamp
ts = read current timestamp
/*F*/ if (write == current position on the ring buffer &&
after < ts && cmpxchg(write_stamp, after, ts)) {
delta = ts - after;
} else {
delta = 0;
}
The assumption is that if the current position on the ring buffer hasn't
moved between C and F, then it also was not interrupted, and that the last
event written has a timestamp that matches the write_stamp. That is the
write_stamp is valid.
But this may not be the case:
If a task context event was interrupted by softirq between B and C.
And the softirq wrote an event that got interrupted by a hard irq between
C and E.
and the hard irq wrote an event (does not need to be interrupted)
We have:
/*B*/ before_stamp = ts of normal context
---> interrupted by softirq
/*B*/ before_stamp = ts of softirq context
---> interrupted by hardirq
/*B*/ before_stamp = ts of hard irq context
/*E*/ write_stamp = ts of hard irq context
/* matches and write_stamp valid */
<----
/*E*/ write_stamp = ts of softirq context
/* No longer matches before_stamp, write_stamp is not valid! */
<---
w != write - length, go to slow path
// Right now the order of events in the ring buffer is:
//
// |-- softirq event --|-- hard irq event --|-- normal context event --|
//
after = write_stamp (this is the ts of softirq)
ts = read current timestamp
if (write == current position on the ring buffer [true] &&
after < ts [true] && cmpxchg(write_stamp, after, ts) [true]) {
delta = ts - after [Wrong!]
The delta is to be between the hard irq event and the normal context
event, but the above logic made the delta between the softirq event and
the normal context event, where the hard irq event is between the two. This
will shift all the remaining event timestamps on the sub-buffer
incorrectly.
The write_stamp is only valid if it matches the before_stamp. The cmpxchg
does nothing to help this.
Instead, the following logic can be done to fix this:
before = before_stamp
ts = read current timestamp
before_stamp = ts
after = write_stamp
if (write == current position on the ring buffer &&
after == before && after < ts) {
delta = ts - after
} else {
delta = 0;
}
The above will only use the write_stamp if it still matches before_stamp
and was tested to not have changed since C.
As a bonus, with this logic we do not need any 64-bit cmpxchg() at all!
This means the 32-bit rb_time_t workaround can finally be removed. But
that's for a later time.
Link: https://lore.kernel.org/linux-trace-kernel/20231218175229.58ec3daf@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231218230712.3a76b081@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Fixes:
|
||
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Linus Torvalds
|
3b8a9b2e68 |
Merge tag 'trace-v6.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt: - Fix eventfs to check creating new files for events with names greater than NAME_MAX. The eventfs lookup needs to check the return result of simple_lookup(). - Fix the ring buffer to check the proper max data size. Events must be able to fit on the ring buffer sub-buffer, if it cannot, then it fails to be written and the logic to add the event is avoided. The code to check if an event can fit failed to add the possible absolute timestamp which may make the event not be able to fit. This causes the ring buffer to go into an infinite loop trying to find a sub-buffer that would fit the event. Luckily, there's a check that will bail out if it looped over a 1000 times and it also warns. The real fix is not to add the absolute timestamp to an event that is starting at the beginning of a sub-buffer because it uses the sub-buffer timestamp. By avoiding the timestamp at the start of the sub-buffer allows events that pass the first check to always find a sub-buffer that it can fit on. - Have large events that do not fit on a trace_seq to print "LINE TOO BIG" like it does for the trace_pipe instead of what it does now which is to silently drop the output. - Fix a memory leak of forgetting to free the spare page that is saved by a trace instance. - Update the size of the snapshot buffer when the main buffer is updated if the snapshot buffer is allocated. - Fix ring buffer timestamp logic by removing all the places that tried to put the before_stamp back to the write stamp so that the next event doesn't add an absolute timestamp. But each of these updates added a race where by making the two timestamp equal, it was validating the write_stamp so that it can be incorrectly used for calculating the delta of an event. - There's a temp buffer used for printing the event that was using the event data size for allocation when it needed to use the size of the entire event (meta-data and payload data) - For hardening, use "%.*s" for printing the trace_marker output, to limit the amount that is printed by the size of the event. This was discovered by development that added a bug that truncated the '\0' and caused a crash. - Fix a use-after-free bug in the use of the histogram files when an instance is being removed. - Remove a useless update in the rb_try_to_discard of the write_stamp. The before_stamp was already changed to force the next event to add an absolute timestamp that the write_stamp is not used. But the write_stamp is modified again using an unneeded 64-bit cmpxchg. - Fix several races in the 32-bit implementation of the rb_time_cmpxchg() that does a 64-bit cmpxchg. - While looking at fixing the 64-bit cmpxchg, I noticed that because the ring buffer uses normal cmpxchg, and this can be done in NMI context, there's some architectures that do not have a working cmpxchg in NMI context. For these architectures, fail recording events that happen in NMI context. * tag 'trace-v6.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Do not record in NMI if the arch does not support cmpxchg in NMI ring-buffer: Have rb_time_cmpxchg() set the msb counter too ring-buffer: Fix 32-bit rb_time_read() race with rb_time_cmpxchg() ring-buffer: Fix a race in rb_time_cmpxchg() for 32 bit archs ring-buffer: Remove useless update to write_stamp in rb_try_to_discard() ring-buffer: Do not try to put back write_stamp tracing: Fix uaf issue when open the hist or hist_debug file tracing: Add size check when printing trace_marker output ring-buffer: Have saved event hold the entire event ring-buffer: Do not update before stamp when switching sub-buffers tracing: Update snapshot buffer on resize if it is allocated ring-buffer: Fix memory leak of free page eventfs: Fix events beyond NAME_MAX blocking tasks tracing: Have large events show up as '[LINE TOO BIG]' instead of nothing ring-buffer: Fix writing to the buffer with max_data_size |
||
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Steven Rostedt (Google)
|
712292308a |
ring-buffer: Do not record in NMI if the arch does not support cmpxchg in NMI
As the ring buffer recording requires cmpxchg() to work, if the architecture does not support cmpxchg in NMI, then do not do any recording within an NMI. Link: https://lore.kernel.org/linux-trace-kernel/20231213175403.6fc18540@gandalf.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
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Steven Rostedt (Google)
|
0aa0e5289c |
ring-buffer: Have rb_time_cmpxchg() set the msb counter too
The rb_time_cmpxchg() on 32-bit architectures requires setting three
32-bit words to represent the 64-bit timestamp, with some salt for
synchronization. Those are: msb, top, and bottom
The issue is, the rb_time_cmpxchg() did not properly salt the msb portion,
and the msb that was written was stale.
Link: https://lore.kernel.org/linux-trace-kernel/20231215084114.20899342@rorschach.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
|
Mathieu Desnoyers
|
dec890089b |
ring-buffer: Fix 32-bit rb_time_read() race with rb_time_cmpxchg()
The following race can cause rb_time_read() to observe a corrupted time
stamp:
rb_time_cmpxchg()
[...]
if (!rb_time_read_cmpxchg(&t->msb, msb, msb2))
return false;
if (!rb_time_read_cmpxchg(&t->top, top, top2))
return false;
<interrupted before updating bottom>
__rb_time_read()
[...]
do {
c = local_read(&t->cnt);
top = local_read(&t->top);
bottom = local_read(&t->bottom);
msb = local_read(&t->msb);
} while (c != local_read(&t->cnt));
*cnt = rb_time_cnt(top);
/* If top and msb counts don't match, this interrupted a write */
if (*cnt != rb_time_cnt(msb))
return false;
^ this check fails to catch that "bottom" is still not updated.
So the old "bottom" value is returned, which is wrong.
Fix this by checking that all three of msb, top, and bottom 2-bit cnt
values match.
The reason to favor checking all three fields over requiring a specific
update order for both rb_time_set() and rb_time_cmpxchg() is because
checking all three fields is more robust to handle partial failures of
rb_time_cmpxchg() when interrupted by nested rb_time_set().
Link: https://lore.kernel.org/lkml/20231211201324.652870-1-mathieu.desnoyers@efficios.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231212193049.680122-1-mathieu.desnoyers@efficios.com
Fixes:
|
||
|
Steven Rostedt (Google)
|
fff88fa0fb |
ring-buffer: Fix a race in rb_time_cmpxchg() for 32 bit archs
Mathieu Desnoyers pointed out an issue in the rb_time_cmpxchg() for 32 bit
architectures. That is:
static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set)
{
unsigned long cnt, top, bottom, msb;
unsigned long cnt2, top2, bottom2, msb2;
u64 val;
/* The cmpxchg always fails if it interrupted an update */
if (!__rb_time_read(t, &val, &cnt2))
return false;
if (val != expect)
return false;
<<<< interrupted here!
cnt = local_read(&t->cnt);
The problem is that the synchronization counter in the rb_time_t is read
*after* the value of the timestamp is read. That means if an interrupt
were to come in between the value being read and the counter being read,
it can change the value and the counter and the interrupted process would
be clueless about it!
The counter needs to be read first and then the value. That way it is easy
to tell if the value is stale or not. If the counter hasn't been updated,
then the value is still good.
Link: https://lore.kernel.org/linux-trace-kernel/20231211201324.652870-1-mathieu.desnoyers@efficios.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231212115301.7a9c9a64@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
083e9f65bd |
ring-buffer: Remove useless update to write_stamp in rb_try_to_discard()
When filtering is enabled, a temporary buffer is created to place the
content of the trace event output so that the filter logic can decide
from the trace event output if the trace event should be filtered out or
not. If it is to be filtered out, the content in the temporary buffer is
simply discarded, otherwise it is written into the trace buffer.
But if an interrupt were to come in while a previous event was using that
temporary buffer, the event written by the interrupt would actually go
into the ring buffer itself to prevent corrupting the data on the
temporary buffer. If the event is to be filtered out, the event in the
ring buffer is discarded, or if it fails to discard because another event
were to have already come in, it is turned into padding.
The update to the write_stamp in the rb_try_to_discard() happens after a
fix was made to force the next event after the discard to use an absolute
timestamp by setting the before_stamp to zero so it does not match the
write_stamp (which causes an event to use the absolute timestamp).
But there's an effort in rb_try_to_discard() to put back the write_stamp
to what it was before the event was added. But this is useless and
wasteful because nothing is going to be using that write_stamp for
calculations as it still will not match the before_stamp.
Remove this useless update, and in doing so, we remove another
cmpxchg64()!
Also update the comments to reflect this change as well as remove some
extra white space in another comment.
Link: https://lore.kernel.org/linux-trace-kernel/20231215081810.1f4f38fe@rorschach.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
dd93942570 |
ring-buffer: Do not try to put back write_stamp
If an update to an event is interrupted by another event between the time
the initial event allocated its buffer and where it wrote to the
write_stamp, the code try to reset the write stamp back to the what it had
just overwritten. It knows that it was overwritten via checking the
before_stamp, and if it didn't match what it wrote to the before_stamp
before it allocated its space, it knows it was overwritten.
To put back the write_stamp, it uses the before_stamp it read. The problem
here is that by writing the before_stamp to the write_stamp it makes the
two equal again, which means that the write_stamp can be considered valid
as the last timestamp written to the ring buffer. But this is not
necessarily true. The event that interrupted the event could have been
interrupted in a way that it was interrupted as well, and can end up
leaving with an invalid write_stamp. But if this happens and returns to
this context that uses the before_stamp to update the write_stamp again,
it can possibly incorrectly make it valid, causing later events to have in
correct time stamps.
As it is OK to leave this function with an invalid write_stamp (one that
doesn't match the before_stamp), there's no reason to try to make it valid
again in this case. If this race happens, then just leave with the invalid
write_stamp and the next event to come along will just add a absolute
timestamp and validate everything again.
Bonus points: This gets rid of another cmpxchg64!
Link: https://lore.kernel.org/linux-trace-kernel/20231214222921.193037a7@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Fixes:
|
||
|
Zheng Yejian
|
1cc111b9cd |
tracing: Fix uaf issue when open the hist or hist_debug file
KASAN report following issue. The root cause is when opening 'hist'
file of an instance and accessing 'trace_event_file' in hist_show(),
but 'trace_event_file' has been freed due to the instance being removed.
'hist_debug' file has the same problem. To fix it, call
tracing_{open,release}_file_tr() in file_operations callback to have
the ref count and avoid 'trace_event_file' being freed.
BUG: KASAN: slab-use-after-free in hist_show+0x11e0/0x1278
Read of size 8 at addr ffff242541e336b8 by task head/190
CPU: 4 PID: 190 Comm: head Not tainted 6.7.0-rc5-g26aff849438c #133
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x98/0xf8
show_stack+0x1c/0x30
dump_stack_lvl+0x44/0x58
print_report+0xf0/0x5a0
kasan_report+0x80/0xc0
__asan_report_load8_noabort+0x1c/0x28
hist_show+0x11e0/0x1278
seq_read_iter+0x344/0xd78
seq_read+0x128/0x1c0
vfs_read+0x198/0x6c8
ksys_read+0xf4/0x1e0
__arm64_sys_read+0x70/0xa8
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Allocated by task 188:
kasan_save_stack+0x28/0x50
kasan_set_track+0x28/0x38
kasan_save_alloc_info+0x20/0x30
__kasan_slab_alloc+0x6c/0x80
kmem_cache_alloc+0x15c/0x4a8
trace_create_new_event+0x84/0x348
__trace_add_new_event+0x18/0x88
event_trace_add_tracer+0xc4/0x1a0
trace_array_create_dir+0x6c/0x100
trace_array_create+0x2e8/0x568
instance_mkdir+0x48/0x80
tracefs_syscall_mkdir+0x90/0xe8
vfs_mkdir+0x3c4/0x610
do_mkdirat+0x144/0x200
__arm64_sys_mkdirat+0x8c/0xc0
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Freed by task 191:
kasan_save_stack+0x28/0x50
kasan_set_track+0x28/0x38
kasan_save_free_info+0x34/0x58
__kasan_slab_free+0xe4/0x158
kmem_cache_free+0x19c/0x508
event_file_put+0xa0/0x120
remove_event_file_dir+0x180/0x320
event_trace_del_tracer+0xb0/0x180
__remove_instance+0x224/0x508
instance_rmdir+0x44/0x78
tracefs_syscall_rmdir+0xbc/0x140
vfs_rmdir+0x1cc/0x4c8
do_rmdir+0x220/0x2b8
__arm64_sys_unlinkat+0xc0/0x100
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Link: https://lore.kernel.org/linux-trace-kernel/20231214012153.676155-1-zhengyejian1@huawei.com
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
||
|
Steven Rostedt (Google)
|
60be76eeab |
tracing: Add size check when printing trace_marker output
If for some reason the trace_marker write does not have a nul byte for the string, it will overflow the print: trace_seq_printf(s, ": %s", field->buf); The field->buf could be missing the nul byte. To prevent overflow, add the max size that the buf can be by using the event size and the field location. int max = iter->ent_size - offsetof(struct print_entry, buf); trace_seq_printf(s, ": %*.s", max, field->buf); Link: https://lore.kernel.org/linux-trace-kernel/20231212084444.4619b8ce@gandalf.local.home Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Steven Rostedt (Google)
|
b049525855 |
ring-buffer: Have saved event hold the entire event
For the ring buffer iterator (non-consuming read), the event needs to be
copied into the iterator buffer to make sure that a writer does not
overwrite it while the user is reading it. If a write happens during the
copy, the buffer is simply discarded.
But the temp buffer itself was not big enough. The allocation of the
buffer was only BUF_MAX_DATA_SIZE, which is the maximum data size that can
be passed into the ring buffer and saved. But the temp buffer needs to
hold the meta data as well. That would be BUF_PAGE_SIZE and not
BUF_MAX_DATA_SIZE.
Link: https://lore.kernel.org/linux-trace-kernel/20231212072558.61f76493@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
9e45e39dc2 |
ring-buffer: Do not update before stamp when switching sub-buffers
The ring buffer timestamps are synchronized by two timestamp placeholders.
One is the "before_stamp" and the other is the "write_stamp" (sometimes
referred to as the "after stamp" but only in the comments. These two
stamps are key to knowing how to handle nested events coming in with a
lockless system.
When moving across sub-buffers, the before stamp is updated but the write
stamp is not. There's an effort to put back the before stamp to something
that seems logical in case there's nested events. But as the current event
is about to cross sub-buffers, and so will any new nested event that happens,
updating the before stamp is useless, and could even introduce new race
conditions.
The first event on a sub-buffer simply uses the sub-buffer's timestamp
and keeps a "delta" of zero. The "before_stamp" and "write_stamp" are not
used in the algorithm in this case. There's no reason to try to fix the
before_stamp when this happens.
As a bonus, it removes a cmpxchg() when crossing sub-buffers!
Link: https://lore.kernel.org/linux-trace-kernel/20231211114420.36dde01b@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
d06aff1cb1 |
tracing: Update snapshot buffer on resize if it is allocated
The snapshot buffer is to mimic the main buffer so that when a snapshot is
needed, the snapshot and main buffer are swapped. When the snapshot buffer
is allocated, it is set to the minimal size that the ring buffer may be at
and still functional. When it is allocated it becomes the same size as the
main ring buffer, and when the main ring buffer changes in size, it should
do.
Currently, the resize only updates the snapshot buffer if it's used by the
current tracer (ie. the preemptirqsoff tracer). But it needs to be updated
anytime it is allocated.
When changing the size of the main buffer, instead of looking to see if
the current tracer is utilizing the snapshot buffer, just check if it is
allocated to know if it should be updated or not.
Also fix typo in comment just above the code change.
Link: https://lore.kernel.org/linux-trace-kernel/20231210225447.48476a6a@rorschach.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
17d8017581 |
ring-buffer: Fix memory leak of free page
Reading the ring buffer does a swap of a sub-buffer within the ring buffer
with a empty sub-buffer. This allows the reader to have full access to the
content of the sub-buffer that was swapped out without having to worry
about contention with the writer.
The readers call ring_buffer_alloc_read_page() to allocate a page that
will be used to swap with the ring buffer. When the code is finished with
the reader page, it calls ring_buffer_free_read_page(). Instead of freeing
the page, it stores it as a spare. Then next call to
ring_buffer_alloc_read_page() will return this spare instead of calling
into the memory management system to allocate a new page.
Unfortunately, on freeing of the ring buffer, this spare page is not
freed, and causes a memory leak.
Link: https://lore.kernel.org/linux-trace-kernel/20231210221250.7b9cc83c@rorschach.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
b55b0a0d7c |
tracing: Have large events show up as '[LINE TOO BIG]' instead of nothing
If a large event was added to the ring buffer that is larger than what the
trace_seq can handle, it just drops the output:
~# cat /sys/kernel/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 2/2 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
<...>-859 [001] ..... 141.118951: tracing_mark_write <...>-859 [001] ..... 141.148201: tracing_mark_write: 78901234
Instead, catch this case and add some context:
~# cat /sys/kernel/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 2/2 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
<...>-852 [001] ..... 121.550551: tracing_mark_write[LINE TOO BIG]
<...>-852 [001] ..... 121.550581: tracing_mark_write: 78901234
This now emulates the same output as trace_pipe.
Link: https://lore.kernel.org/linux-trace-kernel/20231209171058.78c1a026@gandalf.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
||
|
Steven Rostedt (Google)
|
b3ae7b67b8 |
ring-buffer: Fix writing to the buffer with max_data_size
The maximum ring buffer data size is the maximum size of data that can be recorded on the ring buffer. Events must be smaller than the sub buffer data size minus any meta data. This size is checked before trying to allocate from the ring buffer because the allocation assumes that the size will fit on the sub buffer. The maximum size was calculated as the size of a sub buffer page (which is currently PAGE_SIZE minus the sub buffer header) minus the size of the meta data of an individual event. But it missed the possible adding of a time stamp for events that are added long enough apart that the event meta data can't hold the time delta. When an event is added that is greater than the current BUF_MAX_DATA_SIZE minus the size of a time stamp, but still less than or equal to BUF_MAX_DATA_SIZE, the ring buffer would go into an infinite loop, looking for a page that can hold the event. Luckily, there's a check for this loop and after 1000 iterations and a warning is emitted and the ring buffer is disabled. But this should never happen. This can happen when a large event is added first, or after a long period where an absolute timestamp is prefixed to the event, increasing its size by 8 bytes. This passes the check and then goes into the algorithm that causes the infinite loop. For events that are the first event on the sub-buffer, it does not need to add a timestamp, because the sub-buffer itself contains an absolute timestamp, and adding one is redundant. The fix is to check if the event is to be the first event on the sub-buffer, and if it is, then do not add a timestamp. This also fixes 32 bit adding a timestamp when a read of before_stamp or write_stamp is interrupted. There's still no need to add that timestamp if the event is going to be the first event on the sub buffer. Also, if the buffer has "time_stamp_abs" set, then also check if the length plus the timestamp is greater than the BUF_MAX_DATA_SIZE. Link: https://lore.kernel.org/all/20231212104549.58863438@gandalf.local.home/ Link: https://lore.kernel.org/linux-trace-kernel/20231212071837.5fdd6c13@gandalf.local.home Link: https://lore.kernel.org/linux-trace-kernel/20231212111617.39e02849@gandalf.local.home Cc: stable@vger.kernel.org Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Fixes: |
||
|
Linus Torvalds
|
17894c2a7a |
Merge tag 'trace-v6.7-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt:
- Snapshot buffer issues:
1. When instances started allowing latency tracers, it uses a
snapshot buffer (another buffer that is not written to but swapped
with the main buffer that is). The snapshot buffer needs to be the
same size as the main buffer. But when the snapshot buffers were
added to instances, the code to make the snapshot equal to the
main buffer still was only doing it for the main buffer and not
the instances.
2. Need to stop the current tracer when resizing the buffers.
Otherwise there can be a race if the tracer decides to make a
snapshot between resizing the main buffer and the snapshot buffer.
3. When a tracer is "stopped" in disables both the main buffer and
the snapshot buffer. This needs to be done for instances and not
only the main buffer, now that instances also have a snapshot
buffer.
- Buffered event for filtering issues:
When filtering is enabled, because events can be dropped often, it is
quicker to copy the event into a temp buffer and write that into the
main buffer if it is not filtered or just drop the event if it is,
than to write the event into the ring buffer and then try to discard
it. This temp buffer is allocated and needs special synchronization
to do so. But there were some issues with that:
1. When disabling the filter and freeing the buffer, a call to all
CPUs is required to stop each per_cpu usage. But the code called
smp_call_function_many() which does not include the current CPU.
If the task is migrated to another CPU when it enables the CPUs
via smp_call_function_many(), it will not enable the one it is
currently on and this causes issues later on. Use
on_each_cpu_mask() instead, which includes the current CPU.
2.When the allocation of the buffered event fails, it can give a
warning. But the buffered event is just an optimization (it's
still OK to write to the ring buffer and free it). Do not WARN in
this case.
3.The freeing of the buffer event requires synchronization. First a
counter is decremented to zero so that no new uses of it will
happen. Then it sets the buffered event to NULL, and finally it
frees the buffered event. There's a synchronize_rcu() between the
counter decrement and the setting the variable to NULL, but only a
smp_wmb() between that and the freeing of the buffer. It is
theoretically possible that a user missed seeing the decrement,
but will use the buffer after it is free. Another
synchronize_rcu() is needed in place of that smp_wmb().
- ring buffer timestamps on 32 bit machines
The ring buffer timestamp on 32 bit machines has to break the 64 bit
number into multiple values as cmpxchg is required on it, and a 64
bit cmpxchg on 32 bit architectures is very slow. The code use to
just use two 32 bit values and make it a 60 bit timestamp where the
other 4 bits were used as counters for synchronization. It later came
known that the timestamp on 32 bit still need all 64 bits in some
cases. So 3 words were created to handle the 64 bits. But issues
arised with this:
1. The synchronization logic still only compared the counter with
the first two, but not with the third number, so the
synchronization could fail unknowingly.
2. A check on discard of an event could race if an event happened
between the discard and updating one of the counters. The counter
needs to be updated (forcing an absolute timestamp and not to use
a delta) before the actual discard happens.
* tag 'trace-v6.7-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Test last update in 32bit version of __rb_time_read()
ring-buffer: Force absolute timestamp on discard of event
tracing: Fix a possible race when disabling buffered events
tracing: Fix a warning when allocating buffered events fails
tracing: Fix incomplete locking when disabling buffered events
tracing: Disable snapshot buffer when stopping instance tracers
tracing: Stop current tracer when resizing buffer
tracing: Always update snapshot buffer size
|
||
|
Steven Rostedt (Google)
|
f458a14534 |
ring-buffer: Test last update in 32bit version of __rb_time_read()
Since 64 bit cmpxchg() is very expensive on 32bit architectures, the
timestamp used by the ring buffer does some interesting tricks to be able
to still have an atomic 64 bit number. It originally just used 60 bits and
broke it up into two 32 bit words where the extra 2 bits were used for
synchronization. But this was not enough for all use cases, and all 64
bits were required.
The 32bit version of the ring buffer timestamp was then broken up into 3
32bit words using the same counter trick. But one update was not done. The
check to see if the read operation was done without interruption only
checked the first two words and not last one (like it had before this
update). Fix it by making sure all three updates happen without
interruption by comparing the initial counter with the last updated
counter.
Link: https://lore.kernel.org/linux-trace-kernel/20231206100050.3100b7bb@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
b2dd797543 |
ring-buffer: Force absolute timestamp on discard of event
There's a race where if an event is discarded from the ring buffer and an
interrupt were to happen at that time and insert an event, the time stamp
is still used from the discarded event as an offset. This can screw up the
timings.
If the event is going to be discarded, set the "before_stamp" to zero.
When a new event comes in, it compares the "before_stamp" with the
"write_stamp" and if they are not equal, it will insert an absolute
timestamp. This will prevent the timings from getting out of sync due to
the discarded event.
Link: https://lore.kernel.org/linux-trace-kernel/20231206100244.5130f9b3@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
|
Petr Pavlu
|
c0591b1ccc |
tracing: Fix a possible race when disabling buffered events
Function trace_buffered_event_disable() is responsible for freeing pages
backing buffered events and this process can run concurrently with
trace_event_buffer_lock_reserve().
The following race is currently possible:
* Function trace_buffered_event_disable() is called on CPU 0. It
increments trace_buffered_event_cnt on each CPU and waits via
synchronize_rcu() for each user of trace_buffered_event to complete.
* After synchronize_rcu() is finished, function
trace_buffered_event_disable() has the exclusive access to
trace_buffered_event. All counters trace_buffered_event_cnt are at 1
and all pointers trace_buffered_event are still valid.
* At this point, on a different CPU 1, the execution reaches
trace_event_buffer_lock_reserve(). The function calls
preempt_disable_notrace() and only now enters an RCU read-side
critical section. The function proceeds and reads a still valid
pointer from trace_buffered_event[CPU1] into the local variable
"entry". However, it doesn't yet read trace_buffered_event_cnt[CPU1]
which happens later.
* Function trace_buffered_event_disable() continues. It frees
trace_buffered_event[CPU1] and decrements
trace_buffered_event_cnt[CPU1] back to 0.
* Function trace_event_buffer_lock_reserve() continues. It reads and
increments trace_buffered_event_cnt[CPU1] from 0 to 1. This makes it
believe that it can use the "entry" that it already obtained but the
pointer is now invalid and any access results in a use-after-free.
Fix the problem by making a second synchronize_rcu() call after all
trace_buffered_event values are set to NULL. This waits on all potential
users in trace_event_buffer_lock_reserve() that still read a previous
pointer from trace_buffered_event.
Link: https://lore.kernel.org/all/20231127151248.7232-2-petr.pavlu@suse.com/
Link: https://lkml.kernel.org/r/20231205161736.19663-4-petr.pavlu@suse.com
Cc: stable@vger.kernel.org
Fixes:
|
||
|
Petr Pavlu
|
34209fe83e |
tracing: Fix a warning when allocating buffered events fails
Function trace_buffered_event_disable() produces an unexpected warning
when the previous call to trace_buffered_event_enable() fails to
allocate pages for buffered events.
The situation can occur as follows:
* The counter trace_buffered_event_ref is at 0.
* The soft mode gets enabled for some event and
trace_buffered_event_enable() is called. The function increments
trace_buffered_event_ref to 1 and starts allocating event pages.
* The allocation fails for some page and trace_buffered_event_disable()
is called for cleanup.
* Function trace_buffered_event_disable() decrements
trace_buffered_event_ref back to 0, recognizes that it was the last
use of buffered events and frees all allocated pages.
* The control goes back to trace_buffered_event_enable() which returns.
The caller of trace_buffered_event_enable() has no information that
the function actually failed.
* Some time later, the soft mode is disabled for the same event.
Function trace_buffered_event_disable() is called. It warns on
"WARN_ON_ONCE(!trace_buffered_event_ref)" and returns.
Buffered events are just an optimization and can handle failures. Make
trace_buffered_event_enable() exit on the first failure and left any
cleanup later to when trace_buffered_event_disable() is called.
Link: https://lore.kernel.org/all/20231127151248.7232-2-petr.pavlu@suse.com/
Link: https://lkml.kernel.org/r/20231205161736.19663-3-petr.pavlu@suse.com
Fixes:
|
||
|
Petr Pavlu
|
7fed14f7ac |
tracing: Fix incomplete locking when disabling buffered events
The following warning appears when using buffered events: [ 203.556451] WARNING: CPU: 53 PID: 10220 at kernel/trace/ring_buffer.c:3912 ring_buffer_discard_commit+0x2eb/0x420 [...] [ 203.670690] CPU: 53 PID: 10220 Comm: stress-ng-sysin Tainted: G E 6.7.0-rc2-default #4 56e6d0fcf5581e6e51eaaecbdaec2a2338c80f3a [ 203.670704] Hardware name: Intel Corp. GROVEPORT/GROVEPORT, BIOS GVPRCRB1.86B.0016.D04.1705030402 05/03/2017 [ 203.670709] RIP: 0010:ring_buffer_discard_commit+0x2eb/0x420 [ 203.735721] Code: 4c 8b 4a 50 48 8b 42 48 49 39 c1 0f 84 b3 00 00 00 49 83 e8 01 75 b1 48 8b 42 10 f0 ff 40 08 0f 0b e9 fc fe ff ff f0 ff 47 08 <0f> 0b e9 77 fd ff ff 48 8b 42 10 f0 ff 40 08 0f 0b e9 f5 fe ff ff [ 203.735734] RSP: 0018:ffffb4ae4f7b7d80 EFLAGS: 00010202 [ 203.735745] RAX: 0000000000000000 RBX: ffffb4ae4f7b7de0 RCX: ffff8ac10662c000 [ 203.735754] RDX: ffff8ac0c750be00 RSI: ffff8ac10662c000 RDI: ffff8ac0c004d400 [ 203.781832] RBP: ffff8ac0c039cea0 R08: 0000000000000000 R09: 0000000000000000 [ 203.781839] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 203.781842] R13: ffff8ac10662c000 R14: ffff8ac0c004d400 R15: ffff8ac10662c008 [ 203.781846] FS: 00007f4cd8a67740(0000) GS:ffff8ad798880000(0000) knlGS:0000000000000000 [ 203.781851] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 203.781855] CR2: 0000559766a74028 CR3: 00000001804c4000 CR4: 00000000001506f0 [ 203.781862] Call Trace: [ 203.781870] <TASK> [ 203.851949] trace_event_buffer_commit+0x1ea/0x250 [ 203.851967] trace_event_raw_event_sys_enter+0x83/0xe0 [ 203.851983] syscall_trace_enter.isra.0+0x182/0x1a0 [ 203.851990] do_syscall_64+0x3a/0xe0 [ 203.852075] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 203.852090] RIP: 0033:0x7f4cd870fa77 [ 203.982920] Code: 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 90 b8 89 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e9 43 0e 00 f7 d8 64 89 01 48 [ 203.982932] RSP: 002b:00007fff99717dd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000089 [ 203.982942] RAX: ffffffffffffffda RBX: 0000558ea1d7b6f0 RCX: 00007f4cd870fa77 [ 203.982948] RDX: 0000000000000000 RSI: 00007fff99717de0 RDI: 0000558ea1d7b6f0 [ 203.982957] RBP: 00007fff99717de0 R08: 00007fff997180e0 R09: 00007fff997180e0 [ 203.982962] R10: 00007fff997180e0 R11: 0000000000000246 R12: 00007fff99717f40 [ 204.049239] R13: 00007fff99718590 R14: 0000558e9f2127a8 R15: 00007fff997180b0 [ 204.049256] </TASK> For instance, it can be triggered by running these two commands in parallel: $ while true; do echo hist:key=id.syscall:val=hitcount > \ /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger; done $ stress-ng --sysinfo $(nproc) The warning indicates that the current ring_buffer_per_cpu is not in the committing state. It happens because the active ring_buffer_event doesn't actually come from the ring_buffer_per_cpu but is allocated from trace_buffered_event. The bug is in function trace_buffered_event_disable() where the following normally happens: * The code invokes disable_trace_buffered_event() via smp_call_function_many() and follows it by synchronize_rcu(). This increments the per-CPU variable trace_buffered_event_cnt on each target CPU and grants trace_buffered_event_disable() the exclusive access to the per-CPU variable trace_buffered_event. * Maintenance is performed on trace_buffered_event, all per-CPU event buffers get freed. * The code invokes enable_trace_buffered_event() via smp_call_function_many(). This decrements trace_buffered_event_cnt and releases the access to trace_buffered_event. A problem is that smp_call_function_many() runs a given function on all target CPUs except on the current one. The following can then occur: * Task X executing trace_buffered_event_disable() runs on CPU 0. * The control reaches synchronize_rcu() and the task gets rescheduled on another CPU 1. * The RCU synchronization finishes. At this point, trace_buffered_event_disable() has the exclusive access to all trace_buffered_event variables except trace_buffered_event[CPU0] because trace_buffered_event_cnt[CPU0] is never incremented and if the buffer is currently unused, remains set to 0. * A different task Y is scheduled on CPU 0 and hits a trace event. The code in trace_event_buffer_lock_reserve() sees that trace_buffered_event_cnt[CPU0] is set to 0 and decides the use the buffer provided by trace_buffered_event[CPU0]. * Task X continues its execution in trace_buffered_event_disable(). The code incorrectly frees the event buffer pointed by trace_buffered_event[CPU0] and resets the variable to NULL. * Task Y writes event data to the now freed buffer and later detects the created inconsistency. The issue is observable since commit |
||
|
Steven Rostedt (Google)
|
b538bf7d0e |
tracing: Disable snapshot buffer when stopping instance tracers
It use to be that only the top level instance had a snapshot buffer (for
latency tracers like wakeup and irqsoff). When stopping a tracer in an
instance would not disable the snapshot buffer. This could have some
unintended consequences if the irqsoff tracer is enabled.
Consolidate the tracing_start/stop() with tracing_start/stop_tr() so that
all instances behave the same. The tracing_start/stop() functions will
just call their respective tracing_start/stop_tr() with the global_array
passed in.
Link: https://lkml.kernel.org/r/20231205220011.041220035@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes:
|
||
|
Steven Rostedt (Google)
|
d78ab79270 |
tracing: Stop current tracer when resizing buffer
When the ring buffer is being resized, it can cause side effects to the
running tracer. For instance, there's a race with irqsoff tracer that
swaps individual per cpu buffers between the main buffer and the snapshot
buffer. The resize operation modifies the main buffer and then the
snapshot buffer. If a swap happens in between those two operations it will
break the tracer.
Simply stop the running tracer before resizing the buffers and enable it
again when finished.
Link: https://lkml.kernel.org/r/20231205220010.748996423@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes:
|
||
|
Steven Rostedt (Google)
|
7be76461f3 |
tracing: Always update snapshot buffer size
It use to be that only the top level instance had a snapshot buffer (for
latency tracers like wakeup and irqsoff). The update of the ring buffer
size would check if the instance was the top level and if so, it would
also update the snapshot buffer as it needs to be the same as the main
buffer.
Now that lower level instances also has a snapshot buffer, they too need
to update their snapshot buffer sizes when the main buffer is changed,
otherwise the following can be triggered:
# cd /sys/kernel/tracing
# echo 1500 > buffer_size_kb
# mkdir instances/foo
# echo irqsoff > instances/foo/current_tracer
# echo 1000 > instances/foo/buffer_size_kb
Produces:
WARNING: CPU: 2 PID: 856 at kernel/trace/trace.c:1938 update_max_tr_single.part.0+0x27d/0x320
Which is:
ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->array_buffer.buffer, cpu);
if (ret == -EBUSY) {
[..]
}
WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY); <== here
That's because ring_buffer_swap_cpu() has:
int ret = -EINVAL;
[..]
/* At least make sure the two buffers are somewhat the same */
if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages)
goto out;
[..]
out:
return ret;
}
Instead, update all instances' snapshot buffer sizes when their main
buffer size is updated.
Link: https://lkml.kernel.org/r/20231205220010.454662151@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes:
|
||
|
Jens Axboe
|
9fd7874c0e |
iov_iter: replace import_single_range() with import_ubuf()
With the removal of the 'iov' argument to import_single_range(), the two functions are now fully identical. Convert the import_single_range() callers to import_ubuf(), and remove the former fully. Signed-off-by: Jens Axboe <axboe@kernel.dk> Link: https://lore.kernel.org/r/20231204174827.1258875-3-axboe@kernel.dk Signed-off-by: Christian Brauner <brauner@kernel.org> |
||
|
Jens Axboe
|
6ac805d138 |
iov_iter: remove unused 'iov' argument from import_single_range()
It is entirely unused, just get rid of it. Signed-off-by: Jens Axboe <axboe@kernel.dk> Link: https://lore.kernel.org/r/20231204174827.1258875-2-axboe@kernel.dk Signed-off-by: Christian Brauner <brauner@kernel.org> |
||
|
Kees Cook
|
8a3750ecf8 |
tracing/uprobe: Replace strlcpy() with strscpy()
strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated[1]. Additionally, it returns the size of the source string, not the resulting size of the destination string. In an effort to remove strlcpy() completely[2], replace strlcpy() here with strscpy(). The negative return value is already handled by this code so no new handling is needed here. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1] Link: https://github.com/KSPP/linux/issues/89 [2] Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: linux-trace-kernel@vger.kernel.org Acked-by: "Masami Hiramatsu (Google)" <mhiramat@kernel.org> Link: https://lore.kernel.org/r/20231130205607.work.463-kees@kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> |
||
|
Masami Hiramatsu (Google)
|
a1461f1fd6 |
rethook: Use __rcu pointer for rethook::handler
Since the rethook::handler is an RCU-maganged pointer so that it will
notice readers the rethook is stopped (unregistered) or not, it should
be an __rcu pointer and use appropriate functions to be accessed. This
will use appropriate memory barrier when accessing it. OTOH,
rethook::data is never changed, so we don't need to check it in
get_kretprobe().
NOTE: To avoid sparse warning, rethook::handler is defined by a raw
function pointer type with __rcu instead of rethook_handler_t.
Link: https://lore.kernel.org/all/170126066201.398836.837498688669005979.stgit@devnote2/
Fixes:
|
||
|
Yujie Liu
|
f032c53bea |
tracing/kprobes: Fix the order of argument descriptions
The order of descriptions should be consistent with the argument list of
the function, so "kretprobe" should be the second one.
int __kprobe_event_gen_cmd_start(struct dynevent_cmd *cmd, bool kretprobe,
const char *name, const char *loc, ...)
Link: https://lore.kernel.org/all/20231031041305.3363712-1-yujie.liu@intel.com/
Fixes:
|
||
|
Masami Hiramatsu (Google)
|
ce51e6153f |
tracing: fprobe-event: Fix to check tracepoint event and return
Fix to check the tracepoint event is not valid with $retval. The commit |
||
|
Linus Torvalds
|
89cdf9d556 |
Merge tag 'net-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Jakub Kicinski:
"Including fixes from netfilter and bpf.
Current release - regressions:
- sched: fix SKB_NOT_DROPPED_YET splat under debug config
Current release - new code bugs:
- tcp:
- fix usec timestamps with TCP fastopen
- fix possible out-of-bounds reads in tcp_hash_fail()
- fix SYN option room calculation for TCP-AO
- tcp_sigpool: fix some off by one bugs
- bpf: fix compilation error without CGROUPS
- ptp:
- ptp_read() should not release queue
- fix tsevqs corruption
Previous releases - regressions:
- llc: verify mac len before reading mac header
Previous releases - always broken:
- bpf:
- fix check_stack_write_fixed_off() to correctly spill imm
- fix precision tracking for BPF_ALU | BPF_TO_BE | BPF_END
- check map->usercnt after timer->timer is assigned
- dsa: lan9303: consequently nested-lock physical MDIO
- dccp/tcp: call security_inet_conn_request() after setting IP addr
- tg3: fix the TX ring stall due to incorrect full ring handling
- phylink: initialize carrier state at creation
- ice: fix direction of VF rules in switchdev mode
Misc:
- fill in a bunch of missing MODULE_DESCRIPTION()s, more to come"
* tag 'net-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (84 commits)
net: ti: icss-iep: fix setting counter value
ptp: fix corrupted list in ptp_open
ptp: ptp_read should not release queue
net_sched: sch_fq: better validate TCA_FQ_WEIGHTS and TCA_FQ_PRIOMAP
net: kcm: fill in MODULE_DESCRIPTION()
net/sched: act_ct: Always fill offloading tuple iifidx
netfilter: nat: fix ipv6 nat redirect with mapped and scoped addresses
netfilter: xt_recent: fix (increase) ipv6 literal buffer length
ipvs: add missing module descriptions
netfilter: nf_tables: remove catchall element in GC sync path
netfilter: add missing module descriptions
drivers/net/ppp: use standard array-copy-function
net: enetc: shorten enetc_setup_xdp_prog() error message to fit NETLINK_MAX_FMTMSG_LEN
virtio/vsock: Fix uninit-value in virtio_transport_recv_pkt()
r8169: respect userspace disabling IFF_MULTICAST
selftests/bpf: get trusted cgrp from bpf_iter__cgroup directly
bpf: Let verifier consider {task,cgroup} is trusted in bpf_iter_reg
net: phylink: initialize carrier state at creation
test/vsock: add dobule bind connect test
test/vsock: refactor vsock_accept
...
|
||
|
Linus Torvalds
|
31e5f934ff |
Merge tag 'trace-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt: - Remove eventfs_file descriptor This is the biggest change, and the second part of making eventfs create its files dynamically. In 6.6 the first part was added, and that maintained a one to one mapping between eventfs meta descriptors and the directories and file inodes and dentries that were dynamically created. The directories were represented by a eventfs_inode and the files were represented by a eventfs_file. In v6.7 the eventfs_file is removed. As all events have the same directory make up (sched_switch has an "enable", "id", "format", etc files), the handing of what files are underneath each leaf eventfs directory is moved back to the tracing subsystem via a callback. When an event is added to the eventfs, it registers an array of evenfs_entry's. These hold the names of the files and the callbacks to call when the file is referenced. The callback gets the name so that the same callback may be used by multiple files. The callback then supplies the filesystem_operations structure needed to create this file. This has brought the memory footprint of creating multiple eventfs instances down by 2 megs each! - User events now has persistent events that are not associated to a single processes. These are privileged events that hang around even if no process is attached to them - Clean up of seq_buf There's talk about using seq_buf more to replace strscpy() and friends. But this also requires some minor modifications of seq_buf to be able to do this - Expand instance ring buffers individually Currently if boot up creates an instance, and a trace event is enabled on that instance, the ring buffer for that instance and the top level ring buffer are expanded (1.4 MB per CPU). This wastes memory as this happens when nothing is using the top level instance - Other minor clean ups and fixes * tag 'trace-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (34 commits) seq_buf: Export seq_buf_puts() seq_buf: Export seq_buf_putc() eventfs: Use simple_recursive_removal() to clean up dentries eventfs: Remove special processing of dput() of events directory eventfs: Delete eventfs_inode when the last dentry is freed eventfs: Hold eventfs_mutex when calling callback functions eventfs: Save ownership and mode eventfs: Test for ei->is_freed when accessing ei->dentry eventfs: Have a free_ei() that just frees the eventfs_inode eventfs: Remove "is_freed" union with rcu head eventfs: Fix kerneldoc of eventfs_remove_rec() tracing: Have the user copy of synthetic event address use correct context eventfs: Remove extra dget() in eventfs_create_events_dir() tracing: Have trace_event_file have ref counters seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str() eventfs: Fix typo in eventfs_inode union comment eventfs: Fix WARN_ON() in create_file_dentry() powerpc: Remove initialisation of readpos tracing/histograms: Simplify last_cmd_set() seq_buf: fix a misleading comment ... |
||
|
Dave Marchevsky
|
391145ba2a |
bpf: Add __bpf_kfunc_{start,end}_defs macros
BPF kfuncs are meant to be called from BPF programs. Accordingly, most
kfuncs are not called from anywhere in the kernel, which the
-Wmissing-prototypes warning is unhappy about. We've peppered
__diag_ignore_all("-Wmissing-prototypes", ... everywhere kfuncs are
defined in the codebase to suppress this warning.
This patch adds two macros meant to bound one or many kfunc definitions.
All existing kfunc definitions which use these __diag calls to suppress
-Wmissing-prototypes are migrated to use the newly-introduced macros.
A new __diag_ignore_all - for "-Wmissing-declarations" - is added to the
__bpf_kfunc_start_defs macro based on feedback from Andrii on an earlier
version of this patch [0] and another recent mailing list thread [1].
In the future we might need to ignore different warnings or do other
kfunc-specific things. This change will make it easier to make such
modifications for all kfunc defs.
[0]: https://lore.kernel.org/bpf/CAEf4BzaE5dRWtK6RPLnjTW-MW9sx9K3Fn6uwqCTChK2Dcb1Xig@mail.gmail.com/
[1]: https://lore.kernel.org/bpf/ZT+2qCc%2FaXep0%2FLf@krava/
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20231031215625.2343848-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
||
|
Steven Rostedt (Google)
|
4f7969bcd6 |
tracing: Have the user copy of synthetic event address use correct context
A synthetic event is created by the synthetic event interface that can
read both user or kernel address memory. In reality, it reads any
arbitrary memory location from within the kernel. If the address space is
in USER (where CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE is set) then
it uses strncpy_from_user_nofault() to copy strings otherwise it uses
strncpy_from_kernel_nofault().
But since both functions use the same variable there's no annotation to
what that variable is (ie. __user). This makes sparse complain.
Quiet sparse by typecasting the strncpy_from_user_nofault() variable to
a __user pointer.
Link: https://lore.kernel.org/linux-trace-kernel/20231031151033.73c42e23@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
bb32500fb9 |
tracing: Have trace_event_file have ref counters
The following can crash the kernel:
# cd /sys/kernel/tracing
# echo 'p:sched schedule' > kprobe_events
# exec 5>>events/kprobes/sched/enable
# > kprobe_events
# exec 5>&-
The above commands:
1. Change directory to the tracefs directory
2. Create a kprobe event (doesn't matter what one)
3. Open bash file descriptor 5 on the enable file of the kprobe event
4. Delete the kprobe event (removes the files too)
5. Close the bash file descriptor 5
The above causes a crash!
BUG: kernel NULL pointer dereference, address: 0000000000000028
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 6 PID: 877 Comm: bash Not tainted 6.5.0-rc4-test-00008-g2c6b6b1029d4-dirty #186
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:tracing_release_file_tr+0xc/0x50
What happens here is that the kprobe event creates a trace_event_file
"file" descriptor that represents the file in tracefs to the event. It
maintains state of the event (is it enabled for the given instance?).
Opening the "enable" file gets a reference to the event "file" descriptor
via the open file descriptor. When the kprobe event is deleted, the file is
also deleted from the tracefs system which also frees the event "file"
descriptor.
But as the tracefs file is still opened by user space, it will not be
totally removed until the final dput() is called on it. But this is not
true with the event "file" descriptor that is already freed. If the user
does a write to or simply closes the file descriptor it will reference the
event "file" descriptor that was just freed, causing a use-after-free bug.
To solve this, add a ref count to the event "file" descriptor as well as a
new flag called "FREED". The "file" will not be freed until the last
reference is released. But the FREE flag will be set when the event is
removed to prevent any more modifications to that event from happening,
even if there's still a reference to the event "file" descriptor.
Link: https://lore.kernel.org/linux-trace-kernel/20231031000031.1e705592@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231031122453.7a48b923@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes:
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Linus Torvalds
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05bf73aa27 |
Merge tag 'probes-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull probes updates from Masami Hiramatsu:
"Cleanups:
- kprobes: Fixes typo in kprobes samples
- tracing/eprobes: Remove 'break' after return
kretprobe/fprobe performance improvements:
- lib: Introduce new `objpool`, which is a high performance lockless
object queue. This uses per-cpu ring array to allocate/release
objects from the pre-allocated object pool.
Since the index of ring array is a 32bit sequential counter, we can
retry to push/pop the object pointer from the ring without lock (as
seq-lock does)
- lib: Add an objpool test module to test the functionality and
evaluate the performance under some circumstances
- kprobes/fprobe: Improve kretprobe and rethook scalability
performance with objpool.
This improves both legacy kretprobe and fprobe exit handler (which
is based on rethook) to be scalable on SMP systems. Even with
8-threads parallel test, it shows a great scalability improvement
- Remove unneeded freelist.h which is replaced by objpool
- objpool: Add maintainers entry for the objpool
- objpool: Fix to remove unused include header lines"
* tag 'probes-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
kprobes: unused header files removed
MAINTAINERS: objpool added
kprobes: freelist.h removed
kprobes: kretprobe scalability improvement
lib: objpool test module added
lib: objpool added: ring-array based lockless MPMC
tracing/eprobe: drop unneeded breaks
samples: kprobes: Fixes a typo
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Linus Torvalds
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89ed67ef12 |
Merge tag 'net-next-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core & protocols:
- Support usec resolution of TCP timestamps, enabled selectively by a
route attribute.
- Defer regular TCP ACK while processing socket backlog, try to send
a cumulative ACK at the end. Increase single TCP flow performance
on a 200Gbit NIC by 20% (100Gbit -> 120Gbit).
- The Fair Queuing (FQ) packet scheduler:
- add built-in 3 band prio / WRR scheduling
- support bypass if the qdisc is mostly idle (5% speed up for TCP RR)
- improve inactive flow reporting
- optimize the layout of structures for better cache locality
- Support TCP Authentication Option (RFC 5925, TCP-AO), a more modern
replacement for the old MD5 option.
- Add more retransmission timeout (RTO) related statistics to
TCP_INFO.
- Support sending fragmented skbs over vsock sockets.
- Make sure we send SIGPIPE for vsock sockets if socket was
shutdown().
- Add sysctl for ignoring lower limit on lifetime in Router
Advertisement PIO, based on an in-progress IETF draft.
- Add sysctl to control activation of TCP ping-pong mode.
- Add sysctl to make connection timeout in MPTCP configurable.
- Support rcvlowat and notsent_lowat on MPTCP sockets, to help apps
limit the number of wakeups.
- Support netlink GET for MDB (multicast forwarding), allowing user
space to request a single MDB entry instead of dumping the entire
table.
- Support selective FDB flushing in the VXLAN tunnel driver.
- Allow limiting learned FDB entries in bridges, prevent OOM attacks.
- Allow controlling via configfs netconsole targets which were
created via the kernel cmdline at boot, rather than via configfs at
runtime.
- Support multiple PTP timestamp event queue readers with different
filters.
- MCTP over I3C.
BPF:
- Add new veth-like netdevice where BPF program defines the logic of
the xmit routine. It can operate in L3 and L2 mode.
- Support exceptions - allow asserting conditions which should never
be true but are hard for the verifier to infer. With some extra
flexibility around handling of the exit / failure:
https://lwn.net/Articles/938435/
- Add support for local per-cpu kptr, allow allocating and storing
per-cpu objects in maps. Access to those objects operates on the
value for the current CPU.
This allows to deprecate local one-off implementations of per-CPU
storage like BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE maps.
- Extend cgroup BPF sockaddr hooks for UNIX sockets. The use case is
for systemd to re-implement the LogNamespace feature which allows
running multiple instances of systemd-journald to process the logs
of different services.
- Enable open-coded task_vma iteration, after maple tree conversion
made it hard to directly walk VMAs in tracing programs.
- Add open-coded task, css_task and css iterator support. One of the
use cases is customizable OOM victim selection via BPF.
- Allow source address selection with bpf_*_fib_lookup().
- Add ability to pin BPF timer to the current CPU.
- Prevent creation of infinite loops by combining tail calls and
fentry/fexit programs.
- Add missed stats for kprobes to retrieve the number of missed
kprobe executions and subsequent executions of BPF programs.
- Inherit system settings for CPU security mitigations.
- Add BPF v4 CPU instruction support for arm32 and s390x.
Changes to common code:
- overflow: add DEFINE_FLEX() for on-stack definition of structs with
flexible array members.
- Process doc update with more guidance for reviewers.
Driver API:
- Simplify locking in WiFi (cfg80211 and mac80211 layers), use wiphy
mutex in most places and remove a lot of smaller locks.
- Create a common DPLL configuration API. Allow configuring and
querying state of PLL circuits used for clock syntonization, in
network time distribution.
- Unify fragmented and full page allocation APIs in page pool code.
Let drivers be ignorant of PAGE_SIZE.
- Rework PHY state machine to avoid races with calls to phy_stop().
- Notify DSA drivers of MAC address changes on user ports, improve
correctness of offloads which depend on matching port MAC
addresses.
- Allow antenna control on injected WiFi frames.
- Reduce the number of variants of napi_schedule().
- Simplify error handling when composing devlink health messages.
Misc:
- A lot of KCSAN data race "fixes", from Eric.
- A lot of __counted_by() annotations, from Kees.
- A lot of strncpy -> strscpy and printf format fixes.
- Replace master/slave terminology with conduit/user in DSA drivers.
- Handful of KUnit tests for netdev and WiFi core.
Removed:
- AppleTalk COPS.
- AppleTalk ipddp.
- TI AR7 CPMAC Ethernet driver.
Drivers:
- Ethernet high-speed NICs:
- Intel (100G, ice, idpf):
- add a driver for the Intel E2000 IPUs
- make CRC/FCS stripping configurable
- cross-timestamping for E823 devices
- basic support for E830 devices
- use aux-bus for managing client drivers
- i40e: report firmware versions via devlink
- nVidia/Mellanox:
- support 4-port NICs
- increase max number of channels to 256
- optimize / parallelize SF creation flow
- Broadcom (bnxt):
- enhance NIC temperature reporting
- support PAM4 speeds and lane configuration
- Marvell OcteonTX2:
- PTP pulse-per-second output support
- enable hardware timestamping for VFs
- Solarflare/AMD:
- conntrack NAT offload and offload for tunnels
- Wangxun (ngbe/txgbe):
- expose HW statistics
- Pensando/AMD:
- support PCI level reset
- narrow down the condition under which skbs are linearized
- Netronome/Corigine (nfp):
- support CHACHA20-POLY1305 crypto in IPsec offload
- Ethernet NICs embedded, slower, virtual:
- Synopsys (stmmac):
- add Loongson-1 SoC support
- enable use of HW queues with no offload capabilities
- enable PPS input support on all 5 channels
- increase TX coalesce timer to 5ms
- RealTek USB (r8152): improve efficiency of Rx by using GRO frags
- xen: support SW packet timestamping
- add drivers for implementations based on TI's PRUSS (AM64x EVM)
- nVidia/Mellanox Ethernet datacenter switches:
- avoid poor HW resource use on Spectrum-4 by better block
selection for IPv6 multicast forwarding and ordering of blocks
in ACL region
- Ethernet embedded switches:
- Microchip:
- support configuring the drive strength for EMI compliance
- ksz9477: partial ACL support
- ksz9477: HSR offload
- ksz9477: Wake on LAN
- Realtek:
- rtl8366rb: respect device tree config of the CPU port
- Ethernet PHYs:
- support Broadcom BCM5221 PHYs
- TI dp83867: support hardware LED blinking
- CAN:
- add support for Linux-PHY based CAN transceivers
- at91_can: clean up and use rx-offload helpers
- WiFi:
- MediaTek (mt76):
- new sub-driver for mt7925 USB/PCIe devices
- HW wireless <> Ethernet bridging in MT7988 chips
- mt7603/mt7628 stability improvements
- Qualcomm (ath12k):
- WCN7850:
- enable 320 MHz channels in 6 GHz band
- hardware rfkill support
- enable IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS to
make scan faster
- read board data variant name from SMBIOS
- QCN9274: mesh support
- RealTek (rtw89):
- TDMA-based multi-channel concurrency (MCC)
- Silicon Labs (wfx):
- Remain-On-Channel (ROC) support
- Bluetooth:
- ISO: many improvements for broadcast support
- mark BCM4378/BCM4387 as BROKEN_LE_CODED
- add support for QCA2066
- btmtksdio: enable Bluetooth wakeup from suspend"
* tag 'net-next-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1816 commits)
net: pcs: xpcs: Add 2500BASE-X case in get state for XPCS drivers
net: bpf: Use sockopt_lock_sock() in ip_sock_set_tos()
net: mana: Use xdp_set_features_flag instead of direct assignment
vxlan: Cleanup IFLA_VXLAN_PORT_RANGE entry in vxlan_get_size()
iavf: delete the iavf client interface
iavf: add a common function for undoing the interrupt scheme
iavf: use unregister_netdev
iavf: rely on netdev's own registered state
iavf: fix the waiting time for initial reset
iavf: in iavf_down, don't queue watchdog_task if comms failed
iavf: simplify mutex_trylock+sleep loops
iavf: fix comments about old bit locks
doc/netlink: Update schema to support cmd-cnt-name and cmd-max-name
tools: ynl: introduce option to process unknown attributes or types
ipvlan: properly track tx_errors
netdevsim: Block until all devices are released
nfp: using napi_build_skb() to replace build_skb()
net: dsa: microchip: ksz9477: Fix spelling mistake "Enery" -> "Energy"
net: dsa: microchip: Ensure Stable PME Pin State for Wake-on-LAN
net: dsa: microchip: Refactor switch shutdown routine for WoL preparation
...
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Linus Torvalds
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3b3f874cc1 |
Merge tag 'vfs-6.7.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"This contains the usual miscellaneous features, cleanups, and fixes
for vfs and individual fses.
Features:
- Rename and export helpers that get write access to a mount. They
are used in overlayfs to get write access to the upper mount.
- Print the pretty name of the root device on boot failure. This
helps in scenarios where we would usually only print
"unknown-block(1,2)".
- Add an internal SB_I_NOUMASK flag. This is another part in the
endless POSIX ACL saga in a way.
When POSIX ACLs are enabled via SB_POSIXACL the vfs cannot strip
the umask because if the relevant inode has POSIX ACLs set it might
take the umask from there. But if the inode doesn't have any POSIX
ACLs set then we apply the umask in the filesytem itself. So we end
up with:
(1) no SB_POSIXACL -> strip umask in vfs
(2) SB_POSIXACL -> strip umask in filesystem
The umask semantics associated with SB_POSIXACL allowed filesystems
that don't even support POSIX ACLs at all to raise SB_POSIXACL
purely to avoid umask stripping. That specifically means NFS v4 and
Overlayfs. NFS v4 does it because it delegates this to the server
and Overlayfs because it needs to delegate umask stripping to the
upper filesystem, i.e., the filesystem used as the writable layer.
This went so far that SB_POSIXACL is raised eve on kernels that
don't even have POSIX ACL support at all.
Stop this blatant abuse and add SB_I_NOUMASK which is an internal
superblock flag that filesystems can raise to opt out of umask
handling. That should really only be the two mentioned above. It's
not that we want any filesystems to do this. Ideally we have all
umask handling always in the vfs.
- Make overlayfs use SB_I_NOUMASK too.
- Now that we have SB_I_NOUMASK, stop checking for SB_POSIXACL in
IS_POSIXACL() if the kernel doesn't have support for it. This is a
very old patch but it's only possible to do this now with the wider
cleanup that was done.
- Follow-up work on fake path handling from last cycle. Citing mostly
from Amir:
When overlayfs was first merged, overlayfs files of regular files
and directories, the ones that are installed in file table, had a
"fake" path, namely, f_path is the overlayfs path and f_inode is
the "real" inode on the underlying filesystem.
In v6.5, we took another small step by introducing of the
backing_file container and the file_real_path() helper. This change
allowed vfs and filesystem code to get the "real" path of an
overlayfs backing file. With this change, we were able to make
fsnotify work correctly and report events on the "real" filesystem
objects that were accessed via overlayfs.
This method works fine, but it still leaves the vfs vulnerable to
new code that is not aware of files with fake path. A recent
example is commit
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Kees Cook
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dcc4e5728e |
seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str()
Solve two ergonomic issues with struct seq_buf; 1) Too much boilerplate is required to initialize: struct seq_buf s; char buf[32]; seq_buf_init(s, buf, sizeof(buf)); Instead, we can build this directly on the stack. Provide DECLARE_SEQ_BUF() macro to do this: DECLARE_SEQ_BUF(s, 32); 2) %NUL termination is fragile and requires 2 steps to get a valid C String (and is a layering violation exposing the "internals" of seq_buf): seq_buf_terminate(s); do_something(s->buffer); Instead, we can just return s->buffer directly after terminating it in the refactored seq_buf_terminate(), now known as seq_buf_str(): do_something(seq_buf_str(s)); Link: https://lore.kernel.org/linux-trace-kernel/20231027155634.make.260-kees@kernel.org Link: https://lore.kernel.org/linux-trace-kernel/20231026194033.it.702-kees@kernel.org/ Cc: Yosry Ahmed <yosryahmed@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Justin Stitt <justinstitt@google.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Petr Mladek <pmladek@suse.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Yun Zhou <yun.zhou@windriver.com> Cc: Jacob Keller <jacob.e.keller@intel.com> Cc: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |