CVE-2024-43870: Linux kernel · perf: Fix event leak upon exit
Source GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 29 Oct 2026, 22:52 UTC
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 21 Aug 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
Description
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.
References
- nvd.nist.gov/vuln/detail/CVE-2024-43870 (opens in a new tab)
- git.kernel.org/stable/c/05d3fd599594abf79aad4484bccb2b26e1cb0b51 (opens in a new tab)
- git.kernel.org/stable/c/2fd5ad3f310de22836cdacae919dd99d758a1f1b (opens in a new tab)
- git.kernel.org/stable/c/3d7a63352a93bdb8a1cdf29606bf617d3ac1c22a (opens in a new tab)
- git.kernel.org/stable/c/67fad724f1b568b356c1065d50df46e6b30eb2f7 (opens in a new tab)
- git.kernel.org/stable/c/70882d7fa74f0731492a0d493e8515a4f7131831 (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/01/msg00001.html (opens in a new tab)