`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
`buf` is used in this context as a data buffer with 64 bytes of memory
to be occupied by capi_manufakturer.
We see the caller capi20_get_manufacturer() passes data.manufacturer as
its `buf` argument which is then later passed over to user space. Due to
this, let's keep the NUL-padding that strncpy provided by using
strscpy_pad so as to not leak any stack data.
| cdev->errcode = capi20_get_manufacturer(data.contr, data.manufacturer);
| if (cdev->errcode)
| return -EIO;
|
| if (copy_to_user(argp, data.manufacturer,
| sizeof(data.manufacturer)))
| return -EFAULT;
Perhaps this would also be a good instance to use `strtomem_pad` for but
in my testing the compiler was not able to determine the size of `buf`
-- even with all the hints.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230922-strncpy-drivers-isdn-capi-kcapi-c-v1-1-55fcf8b075fb@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
If, for any reason, the open-coded arithmetic causes a wraparound,
the protection that `struct_size()` adds against potential integer
overflows is defeated. Fix this by hardening call to `struct_size()`
with `size_add()`.
Fixes: b626871a7c ("usb: atm: Use struct_size() helper")
Signed-off-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/ZQSuboEIhvATAdxN@work
Signed-off-by: Kees Cook <keescook@chromium.org>
If, for any reason, the open-coded arithmetic causes a wraparound, the
protection that `struct_size()` adds against potential integer overflows
is defeated. Fix this by hardening call to `struct_size()` with `size_add()`.
Fixes: 40e1a70b4a ("drm: Add GUD USB Display driver")
Signed-off-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/ZQSlyHKPdw/zsy4c@work
Signed-off-by: Kees Cook <keescook@chromium.org>
atomic_t variables are currently used to implement reference counters
with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)
Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows and
underflows. This is important since overflows and underflows can lead
to use-after-free situation and be exploitable.
The variable group_info.usage is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
**Important note for maintainers:
Some functions from refcount_t API defined in refcount.h have different
memory ordering guarantees than their atomic counterparts. Please check
Documentation/core-api/refcount-vs-atomic.rst for more information.
Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in some
rare cases it might matter. Please double check that you don't have
some undocumented memory guarantees for this variable usage.
For the group_info.usage it might make a difference in following places:
- put_group_info(): decrement in refcount_dec_and_test() only
provides RELEASE ordering and ACQUIRE ordering on success vs. fully
ordered atomic counterpart
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Link: https://lore.kernel.org/r/20230818041456.gonna.009-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
It's an oversight to not have already listed Gustavo here. Add him as a
Reviewer.
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Since __counted_by annotations may also require that code be changed to
get initialization ordering correct, let's get an extra group of eyes on
code that is working on these annotations.
Signed-off-by: Kees Cook <keescook@chromium.org>
The lkdtm selftest config fragment enables CONFIG_UBSAN_TRAP to make the
ARRAY_BOUNDS test kill the calling process when an out-of-bound access
is detected by UBSAN. However, after this [1] commit, UBSAN is triggered
under many new scenarios that weren't detected before, such as in struct
definitions with fixed-size trailing arrays used as flexible arrays. As
a result, CONFIG_UBSAN_TRAP=y has become a very aggressive option to
enable except for specific situations.
`make kselftest-merge` applies CONFIG_UBSAN_TRAP=y to the kernel config
for all selftests, which makes many of them fail because of system hangs
during boot.
This change removes the config option from the lkdtm kselftest and
configures the ARRAY_BOUNDS test to look for UBSAN reports rather than
relying on the calling process being killed.
[1] commit 2d47c6956a ("ubsan: Tighten UBSAN_BOUNDS on GCC")'
Signed-off-by: Ricardo Cañuelo <ricardo.canuelo@collabora.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230802063252.1917997-1-ricardo.canuelo@collabora.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Upon a panic() the kernel will use either smp_send_stop() or
crash_smp_send_stop() to attempt to stop secondary CPUs via an IPI,
which may or may not be an NMI. Generally it's preferable that this is an
NMI so that CPUs can be stopped in as many situations as possible, but
it's not always possible to provide an NMI, and there are cases where
CPUs may be unable to handle the NMI regardless.
This patch adds a test for panic() where all other CPUs are stuck with
interrupts disabled, which can be used to check whether the kernel
gracefully handles CPUs failing to respond to a stop, and whether NMIs
actually work to stop CPUs.
For example, on arm64 *without* an NMI, this results in:
| # echo PANIC_STOP_IRQOFF > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry PANIC_STOP_IRQOFF
| Kernel panic - not syncing: panic stop irqoff test
| CPU: 2 PID: 24 Comm: migration/2 Not tainted 6.5.0-rc3-00077-ge6c782389895-dirty #4
| Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
| Stopper: multi_cpu_stop+0x0/0x1a0 <- stop_machine_cpuslocked+0x158/0x1a4
| Call trace:
| dump_backtrace+0x94/0xec
| show_stack+0x18/0x24
| dump_stack_lvl+0x74/0xc0
| dump_stack+0x18/0x24
| panic+0x358/0x3e8
| lkdtm_PANIC+0x0/0x18
| multi_cpu_stop+0x9c/0x1a0
| cpu_stopper_thread+0x84/0x118
| smpboot_thread_fn+0x224/0x248
| kthread+0x114/0x118
| ret_from_fork+0x10/0x20
| SMP: stopping secondary CPUs
| SMP: failed to stop secondary CPUs 0-3
| Kernel Offset: 0x401cf3490000 from 0xffff80008000000c0
| PHYS_OFFSET: 0x40000000
| CPU features: 0x00000000,68c167a1,cce6773f
| Memory Limit: none
| ---[ end Kernel panic - not syncing: panic stop irqoff test ]---
Note the "failed to stop secondary CPUs 0-3" message.
On arm64 *with* an NMI, this results in:
| # echo PANIC_STOP_IRQOFF > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry PANIC_STOP_IRQOFF
| Kernel panic - not syncing: panic stop irqoff test
| CPU: 1 PID: 19 Comm: migration/1 Not tainted 6.5.0-rc3-00077-ge6c782389895-dirty #4
| Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
| Stopper: multi_cpu_stop+0x0/0x1a0 <- stop_machine_cpuslocked+0x158/0x1a4
| Call trace:
| dump_backtrace+0x94/0xec
| show_stack+0x18/0x24
| dump_stack_lvl+0x74/0xc0
| dump_stack+0x18/0x24
| panic+0x358/0x3e8
| lkdtm_PANIC+0x0/0x18
| multi_cpu_stop+0x9c/0x1a0
| cpu_stopper_thread+0x84/0x118
| smpboot_thread_fn+0x224/0x248
| kthread+0x114/0x118
| ret_from_fork+0x10/0x20
| SMP: stopping secondary CPUs
| Kernel Offset: 0x55a9c0bc0000 from 0xffff800080000000
| PHYS_OFFSET: 0x40000000
| CPU features: 0x00000000,68c167a1,fce6773f
| Memory Limit: none
| ---[ end Kernel panic - not syncing: panic stop irqoff test ]---
Note the absence of a "failed to stop secondary CPUs" message, since we
don't log anything when secondary CPUs are successfully stopped.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20230921161634.4063233-1-mark.rutland@arm.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Pull x86 fixes from Ingo Molnar:
"Misc fixes:
- Fix an UV boot crash
- Skip spurious ENDBR generation on _THIS_IP_
- Fix ENDBR use in putuser() asm methods
- Fix corner case boot crashes on 5-level paging
- and fix a false positive WARNING on LTO kernels"
* tag 'x86-urgent-2023-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/purgatory: Remove LTO flags
x86/boot/compressed: Reserve more memory for page tables
x86/ibt: Avoid duplicate ENDBR in __put_user_nocheck*()
x86/ibt: Suppress spurious ENDBR
x86/platform/uv: Use alternate source for socket to node data
Pull scheduler fixes from Ingo Molnar:
"Fix a performance regression on large SMT systems, an Intel SMT4
balancing bug, and a topology setup bug on (Intel) hybrid processors"
* tag 'sched-urgent-2023-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/sched: Restore the SD_ASYM_PACKING flag in the DIE domain
sched/fair: Fix SMT4 group_smt_balance handling
sched/fair: Optimize should_we_balance() for large SMT systems
Pull objtool fix from Ingo Molnar:
"Fix a cold functions related false-positive objtool warning that
triggers on Clang"
* tag 'objtool-urgent-2023-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix _THIS_IP_ detection for cold functions
Pull WARN fix from Ingo Molnar:
"Fix a missing preempt-enable in the WARN() slowpath"
* tag 'core-urgent-2023-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
panic: Reenable preemption in WARN slowpath
The choose_32_64() macros were added to deal with an odd inconsistency
between the 32-bit and 64-bit layout of 'struct stat' way back when in
commit a52dd971f9 ("vfs: de-crapify "cp_new_stat()" function").
Then a decade later Mikulas noticed that said inconsistency had been a
mistake in the early x86-64 port, and shouldn't have existed in the
first place. So commit 932aba1e16 ("stat: fix inconsistency between
struct stat and struct compat_stat") removed the uses of the helpers.
But the helpers remained around, unused.
Get rid of them.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull smb client fixes from Steve French:
"Three small SMB3 client fixes, one to improve a null check and two
minor cleanups"
* tag '6.6-rc1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
smb3: fix some minor typos and repeated words
smb3: correct places where ENOTSUPP is used instead of preferred EOPNOTSUPP
smb3: move server check earlier when setting channel sequence number
Pull smb server fixes from Steve French:
"Two ksmbd server fixes"
* tag '6.6-rc1-ksmbd' of git://git.samba.org/ksmbd:
ksmbd: fix passing freed memory 'aux_payload_buf'
ksmbd: remove unneeded mark_inode_dirty in set_info_sec()
Pull ext4 fixes from Ted Ts'o:
"Regression and bug fixes for ext4"
* tag 'ext4_for_linus-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: fix rec_len verify error
ext4: do not let fstrim block system suspend
ext4: move setting of trimmed bit into ext4_try_to_trim_range()
jbd2: Fix memory leak in journal_init_common()
jbd2: Remove page size assumptions
buffer: Make bh_offset() work for compound pages
-flto* implies -ffunction-sections. With LTO enabled, ld.lld generates
multiple .text sections for purgatory.ro:
$ readelf -S purgatory.ro | grep " .text"
[ 1] .text PROGBITS 0000000000000000 00000040
[ 7] .text.purgatory PROGBITS 0000000000000000 000020e0
[ 9] .text.warn PROGBITS 0000000000000000 000021c0
[13] .text.sha256_upda PROGBITS 0000000000000000 000022f0
[15] .text.sha224_upda PROGBITS 0000000000000000 00002be0
[17] .text.sha256_fina PROGBITS 0000000000000000 00002bf0
[19] .text.sha224_fina PROGBITS 0000000000000000 00002cc0
This causes WARNING from kexec_purgatory_setup_sechdrs():
WARNING: CPU: 26 PID: 110894 at kernel/kexec_file.c:919
kexec_load_purgatory+0x37f/0x390
Fix this by disabling LTO for purgatory.
[ AFAICT, x86 is the only arch that supports LTO and purgatory. ]
We could also fix this with an explicit linker script to rejoin .text.*
sections back into .text. However, given the benefit of LTOing purgatory
is small, simply disable the production of more .text.* sections for now.
Fixes: b33fff07e3 ("x86, build: allow LTO to be selected")
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20230914170138.995606-1-song@kernel.org
