Resource Leak Affecting kernel-debug-uki-virt package, versions <0:5.14.0-503.11.1.el9_5
Threat Intelligence
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Test your applications- Snyk IDSNYK-RHEL9-KERNELDEBUGUKIVIRT-7793238
- published22 Aug 2024
- disclosed21 Aug 2024
Introduced: 21 Aug 2024
CVE-2024-43869 (opens in a new tab)How to fix?
Upgrade RHEL:9 kernel-debug-uki-virt to version 0:5.14.0-503.11.1.el9_5 or higher.
This issue was patched in RHSA-2024:9315.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-debug-uki-virt package and not the kernel-debug-uki-virt package as distributed by RHEL.
See How to fix? for RHEL:9 relevant fixed versions and status.
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() =======> <NMI> perf_event_overflow() event->pending_sigtrap = ... irq_work_queue(&event->pending_irq) <======= </NMI> 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() =======> <IRQ> perf_pending_irq() //do nothing, rely on pending task work <======= </IRQ>
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, preventing it from ever beeing freed.
References
- https://access.redhat.com/security/cve/CVE-2024-43869
- https://git.kernel.org/stable/c/104e258a004037bc7dba9f6085c71dad6af57ad4
- https://git.kernel.org/stable/c/3a5465418f5fd970e86a86c7f4075be262682840
- https://git.kernel.org/stable/c/9ad46f1fef421d43cdab3a7d1744b2f43b54dae0
- https://git.kernel.org/stable/c/ed2c202dac55423a52d7e2290f2888bf08b8ee99
- https://git.kernel.org/stable/c/f34d8307a73a18de5320fcc6f40403146d061891