perf: Fix event leak upon exec and file release
Summary
perf: Fix event leak upon exec and file release
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
perf: Fix event leak upon exec and file release
The perf pending task work is never waited upon the matching event
release. In the case of a child event, released via free_event()
directly, this can potentially result in a leaked event, such as in the
following scenario that doesn't even require a weak IRQ work
implementation to trigger:
schedule()
prepare_task_switch()
=======>
perf_event_overflow()
event->pending_sigtrap = ...
irq_work_queue(&event->pending_irq)
<=======
perf_event_task_sched_out()
event_sched_out()
event->pending_sigtrap = 0;
atomic_long_inc_not_zero(&event->refcount)
task_work_add(&event->pending_task)
finish_lock_switch()
=======>
perf_pending_irq()
//do nothing, rely on pending task work
<=======
begin_new_exec()
perf_event_exit_task()
perf_event_exit_event()
// If is child event
free_event()
WARN(atomic_long_cmpxchg(&event->refcount, 1, 0) != 1)
// event is leaked
Similar scenarios can also happen with perf_event_remove_on_exec() or
simply against concurrent perf_event_release().
Fix this with synchonizing against the possibly remaining pending task
work while freeing the event, just like is done with remaining pending
IRQ work. This means that the pending task callback neither need nor
should hold a reference to the event, preven…
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2024-43869 linux Fixed in: 6.1.106-1
- Ubuntu UBUNTU-CVE-2024-43869 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web lists.debian.org