In the Linux kernel, the following vulnerability has been resolved:
perf: Fix event leak upon exit
When a task is scheduled out, pending sigtrap deliveries are deferred
to the target task upon resume to userspace via task_work.
However failures while adding an event’s callback to the task_work
engine are ignored. And since the last call for events exit happen
after task work is eventually closed, there is a small window during
which pending sigtrap can be queued though ignored, leaking the event
refcount addition such as in the following scenario:
TASK A
-----
do_exit()
exit_task_work(tsk);
<IRQ>
perf_event_overflow()
event->pending_sigtrap = pending_id;
irq_work_queue(&event->pending_irq);
</IRQ>
=========> PREEMPTION: TASK A -> TASK B
event_sched_out()
event->pending_sigtrap = 0;
atomic_long_inc_not_zero(&event->refcount)
// FAILS: task work has exited
task_work_add(&event->pending_task)
[...]
<IRQ WORK>
perf_pending_irq()
// early return: event->oncpu = -1
</IRQ WORK>
[...]
=========> TASK B -> TASK A
perf_event_exit_task(tsk)
perf_event_exit_event()
free_event()
WARN(atomic_long_cmpxchg(&event->refcount, 1, 0) != 1)
// leak event due to unexpected refcount == 2
As a result the event is never released while the task exits.
Fix this with appropriate task_work_add()'s error handling.
Vendor | Product | Version | CPE |
---|---|---|---|
linux | linux_kernel | * | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"kernel/events/core.c"
],
"versions": [
{
"version": "8bffa95ac19f",
"lessThan": "67fad724f1b5",
"status": "affected",
"versionType": "git"
},
{
"version": "517e6a301f34",
"lessThan": "70882d7fa74f",
"status": "affected",
"versionType": "git"
},
{
"version": "517e6a301f34",
"lessThan": "05d3fd599594",
"status": "affected",
"versionType": "git"
},
{
"version": "517e6a301f34",
"lessThan": "3d7a63352a93",
"status": "affected",
"versionType": "git"
},
{
"version": "517e6a301f34",
"lessThan": "2fd5ad3f310d",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"kernel/events/core.c"
],
"versions": [
{
"version": "6.1",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.1",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.15.165",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.1.103",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.6.44",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.10.3",
"lessThanOrEqual": "6.10.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.11",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]
git.kernel.org/stable/c/05d3fd599594abf79aad4484bccb2b26e1cb0b51
git.kernel.org/stable/c/2fd5ad3f310de22836cdacae919dd99d758a1f1b
git.kernel.org/stable/c/3d7a63352a93bdb8a1cdf29606bf617d3ac1c22a
git.kernel.org/stable/c/67fad724f1b568b356c1065d50df46e6b30eb2f7
git.kernel.org/stable/c/70882d7fa74f0731492a0d493e8515a4f7131831