CVE-2024-43869 in Linux
Summary
by MITRE • 08/21/2024
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, preventing it from ever beeing freed.
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Analysis
by VulDB Data Team • 02/18/2026
The vulnerability described in CVE-2024-43869 represents a critical memory management flaw within the Linux kernel's performance monitoring subsystem, specifically affecting the perf event handling mechanism. This issue manifests as a resource leak where perf events fail to be properly cleaned up during process execution transitions, creating persistent references that prevent memory deallocation. The flaw occurs when a child event is released directly through the free_event() function during process execution, leading to scenarios where event structures remain allocated in memory despite being logically removed from the system. The vulnerability is particularly concerning because it operates without requiring any specific system conditions or weak interrupt work implementations to trigger, making it inherently more exploitable than similar issues that depend on external factors.
The technical root cause of this vulnerability lies in the improper synchronization between pending task work and event release operations within the perf subsystem. When a process executes a new program through begin_new_exec(), the perf_event_exit_task() function is invoked, which calls perf_event_exit_event() to handle event cleanup. For child events, this directly leads to free_event() being called, but the function fails to properly synchronize with any pending task work that may still reference the event structure. The event's reference count is checked using atomic_long_cmpxchg(), which should ensure proper cleanup, but this mechanism is insufficient when pending task work callbacks have not yet completed execution. The system maintains a race condition where the event structure can be freed while still being referenced by a pending task work callback, creating a memory leak that persists until the system reboots or the process terminates naturally.
The operational impact of this vulnerability extends beyond simple memory consumption issues, as it represents a potential vector for denial of service attacks and resource exhaustion. When multiple processes repeatedly execute new programs while maintaining perf monitoring, the cumulative effect of leaked event structures can lead to significant memory pressure and system instability. The vulnerability affects the core perf subsystem functionality, which is widely used for performance monitoring, debugging, and profiling across various Linux distributions and kernel versions. This flaw particularly impacts systems where performance monitoring is actively used, such as development environments, production servers, and containerized applications that rely on perf for observability and debugging purposes. The issue can also compound with concurrent perf_event_release() operations, creating additional complexity in the resource management and potentially leading to more severe system stability problems.
Mitigation strategies for CVE-2024-43869 require immediate kernel updates from vendors that have implemented the fix, which synchronizes pending task work with event freeing operations similar to how pending IRQ work is handled. The fix ensures that when an event is freed, the system waits for any pending task work callbacks to complete before allowing the event structure to be deallocated, eliminating the race condition that causes the leak. Organizations should prioritize updating their kernel versions to include this patch, particularly in environments where performance monitoring is actively used. System administrators should monitor for signs of memory exhaustion or performance degradation that might indicate this vulnerability is active, as the leak may not be immediately apparent but can accumulate over time. The fix aligns with security best practices outlined in CWE-401 and follows the ATT&CK framework's approach to resource exhaustion and system stability threats, ensuring proper synchronization and memory management during process transitions. This vulnerability demonstrates the importance of careful synchronization in kernel subsystems and highlights the need for comprehensive testing of resource management operations in multi-threaded and concurrent environments.