NT waits can optionally be made "alertable". This is a special channel for
thread wakeup that is mildly similar to SIGIO. A thread has an internal single
bit of "alerted" state, and if a thread is alerted while an alertable wait, the
wait will return a special value, consume the "alerted" state, and will not
consume any of its objects.
Alerts are implemented using events; the user-space NT emulator is expected to
create an internal ntsync event for each thread and pass that event to wait
functions.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This correspond to the NT syscall NtCreateEvent().
An NT event holds a single bit of state denoting whether it is signaled or
unsignaled.
There are two types of events: manual-reset and automatic-reset. When an
automatic-reset event is acquired via a wait function, its state is reset to
unsignaled. Manual-reset events are not affected by wait functions.
Whether the event is manual-reset, and its initial state, are specified at
creation time.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This does not correspond to any NT syscall. Rather, when a thread dies, it
should be called by the NT emulator for each mutex, with the TID of the dying
thread.
NT mutexes are robust (in the pthread sense). When an NT thread dies, any
mutexes it owned are immediately released. Acquisition of those mutexes by other
threads will return a special value indicating that the mutex was abandoned,
like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed
used here for that purpose.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This corresponds to the NT syscall NtCreateMutant().
An NT mutex is recursive, with a 32-bit recursion counter. When acquired via
NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS
records the thread which acquired it.
The OS records the thread which acquired it. However, in order to keep this
driver self-contained, the owning thread ID is managed by user-space, and passed
as a parameter to all relevant ioctls.
The initial owner and recursion count, if any, are specified when the mutex is
created.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are
simultaneously signaled, and then acquires all of them as a single atomic
operation.
Because acquisition of multiple objects is atomic, some complex locking is
required. We cannot simply spin-lock multiple objects simultaneously, as that
may disable preëmption for a problematically long time.
Instead, modifying any object which may be involved in a wait-all operation takes
a device-wide sleeping mutex, "wait_all_lock", instead of the normal object
spinlock.
Because wait-for-all is a rare operation, in order to optimize wait-for-any,
this lock is only taken when necessary. "all_hint" is used to mark objects which
are involved in a wait-for-all operation, and if an object is not, only its
spinlock is taken.
The locking scheme used here was written by Peter Zijlstra.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This corresponds to part of the functionality of the NT syscall
NtWaitForMultipleObjects(). Specifically, it implements the behaviour where
the third argument (wait_any) is TRUE, and it does not handle alertable waits.
Those features have been split out into separate patches to ease review.
This patch therefore implements the wait/wake infrastructure which comprises the
core of ntsync's functionality.
NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike
poll(), it "consumes" objects when they are signaled. For semaphores, this means
decreasing one from the internal counter. At most one object can be consumed by
this function.
This wait/wake model is fundamentally different from that used anywhere else in
the kernel, and for that reason ntsync does not use any existing infrastructure,
such as futexes, kernel mutexes or semaphores, or wait_event().
Up to 64 objects can be waited on at once. As soon as one is signaled, the
object with the lowest index is consumed, and that index is returned via the
"index" field.
A timeout is supported. The timeout is passed as a u64 nanosecond value, which
represents absolute time measured against either the MONOTONIC or REALTIME clock
(controlled by the flags argument). If U64_MAX is passed, the ioctl waits
indefinitely.
This ioctl validates that all objects belong to the relevant device. This is not
necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be
necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch.
Some padding fields are added for alignment and for fields which will be added
in future patches (split out to ease review).
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
misc_minor_alloc was allocating id using ida for minor only in case of
MISC_DYNAMIC_MINOR but misc_minor_free was always freeing ids
using ida_free causing a mismatch and following warn:
> > WARNING: CPU: 0 PID: 159 at lib/idr.c:525 ida_free+0x3e0/0x41f
> > ida_free called for id=127 which is not allocated.
> > <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
...
> > [<60941eb4>] ida_free+0x3e0/0x41f
> > [<605ac993>] misc_minor_free+0x3e/0xbc
> > [<605acb82>] misc_deregister+0x171/0x1b3
misc_minor_alloc is changed to allocate id from ida for all minors
falling in the range of dynamic/ misc dynamic minors
Fixes: ab760791c0 ("char: misc: Increase the maximum number of dynamic misc devices to 1048448")
Signed-off-by: Vimal Agrawal <vimal.agrawal@sophos.com>
Reviewed-by: Dirk VanDerMerwe <dirk.vandermerwe@sophos.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241021133812.23703-1-vimal.agrawal@sophos.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
IOCTL_VMCI_SOCKETS_VERSION and IOCTL_VMCI_SOCKETS_GET_AF_VALUE were
never implemented, because VSOCK ended up being implemented as a
generic mechanism with a static AF value. Likewise,
IOCTL_VMCI_SOCKETS_GET_LOCAL_CID ended up being implemented as
IOCTL_VM_SOCKETS_GET_LOCAL_CID.
This isn't a UAPI header, so it should be fine to remove the unused
values. I've left a comment noting IOCTL_VM_SOCKETS_GET_LOCAL_CID is
in the VMCI range to avoid unintentional reuse.
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Acked-by: Vishnu Dasa <vishnu.dasa@broadcom.com>
Link: https://lore.kernel.org/r/fzdcrz4yfedokmbm22h2iwsluix4jwejwaltuwcdr6kz3yu6eu@nue5xc6ayevo
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When binderfs is not enabled, the binder driver parses the kernel
config to create all binder devices. All of the new binder devices
are stored in the list binder_devices.
When binderfs is enabled, the binder driver creates new binder devices
dynamically when userspace applications call BINDER_CTL_ADD ioctl. But
the devices created in this way are not stored in the same list.
This patch fixes that.
Signed-off-by: Li Li <dualli@google.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241218212935.4162907-2-dualli@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Sometimes one needs to be able not only to catch PPS signals but to
produce them also. For example, running a distributed simulation,
which requires computers' clock to be synchronized very tightly.
This patch adds PPS generators class in order to have a well-defined
interface for these devices.
Signed-off-by: Rodolfo Giometti <giometti@enneenne.com>
Link: https://lore.kernel.org/r/20241108073115.759039-2-giometti@enneenne.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On a board running ntpd and gpsd, I'm seeing a consistent use-after-free
in sys_exit() from gpsd when rebooting:
pps pps1: removed
------------[ cut here ]------------
kobject: '(null)' (00000000db4bec24): is not initialized, yet kobject_put() is being called.
WARNING: CPU: 2 PID: 440 at lib/kobject.c:734 kobject_put+0x120/0x150
CPU: 2 UID: 299 PID: 440 Comm: gpsd Not tainted 6.11.0-rc6-00308-gb31c44928842 #1
Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT)
pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : kobject_put+0x120/0x150
lr : kobject_put+0x120/0x150
sp : ffffffc0803d3ae0
x29: ffffffc0803d3ae0 x28: ffffff8042dc9738 x27: 0000000000000001
x26: 0000000000000000 x25: ffffff8042dc9040 x24: ffffff8042dc9440
x23: ffffff80402a4620 x22: ffffff8042ef4bd0 x21: ffffff80405cb600
x20: 000000000008001b x19: ffffff8040b3b6e0 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 696e6920746f6e20
x14: 7369203a29343263 x13: 205d303434542020 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
kobject_put+0x120/0x150
cdev_put+0x20/0x3c
__fput+0x2c4/0x2d8
____fput+0x1c/0x38
task_work_run+0x70/0xfc
do_exit+0x2a0/0x924
do_group_exit+0x34/0x90
get_signal+0x7fc/0x8c0
do_signal+0x128/0x13b4
do_notify_resume+0xdc/0x160
el0_svc+0xd4/0xf8
el0t_64_sync_handler+0x140/0x14c
el0t_64_sync+0x190/0x194
---[ end trace 0000000000000000 ]---
...followed by more symptoms of corruption, with similar stacks:
refcount_t: underflow; use-after-free.
kernel BUG at lib/list_debug.c:62!
Kernel panic - not syncing: Oops - BUG: Fatal exception
This happens because pps_device_destruct() frees the pps_device with the
embedded cdev immediately after calling cdev_del(), but, as the comment
above cdev_del() notes, fops for previously opened cdevs are still
callable even after cdev_del() returns. I think this bug has always
been there: I can't explain why it suddenly started happening every time
I reboot this particular board.
In commit d953e0e837 ("pps: Fix a use-after free bug when
unregistering a source."), George Spelvin suggested removing the
embedded cdev. That seems like the simplest way to fix this, so I've
implemented his suggestion, using __register_chrdev() with pps_idr
becoming the source of truth for which minor corresponds to which
device.
But now that pps_idr defines userspace visibility instead of cdev_add(),
we need to be sure the pps->dev refcount can't reach zero while
userspace can still find it again. So, the idr_remove() call moves to
pps_unregister_cdev(), and pps_idr now holds a reference to pps->dev.
pps_core: source serial1 got cdev (251:1)
<...>
pps pps1: removed
pps_core: unregistering pps1
pps_core: deallocating pps1
Fixes: d953e0e837 ("pps: Fix a use-after free bug when unregistering a source.")
Cc: stable@vger.kernel.org
Signed-off-by: Calvin Owens <calvin@wbinvd.org>
Reviewed-by: Michal Schmidt <mschmidt@redhat.com>
Link: https://lore.kernel.org/r/a17975fd5ae99385791929e563f72564edbcf28f.1731383727.git.calvin@wbinvd.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Both ->reg_read() and ->reg_write() return values are not easy to
deduce. Explicit that they should return zero on success (and negative
values otherwise).
Such callbacks, in some alternative world, could return the number of
bytes in the success case. That would be translated to errors in the
nvmem core because of checks like:
ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
if (ret) {
// error case
}
This mistake is not just theoretical, see commit
28b008751a ("nvmem: rmem: Fix return value of rmem_read()").
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20241230143035.265518-4-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
