Linux Kernel Buffer Mapping Failure in perf_mmap() Function

A vulnerability in the Linux kernel's perf subsystem has been addressed. The issue arose in the perf_mmap() function, which handles memory mapping for performance monitoring events. When the function successfully allocates a buffer or attaches to an existing one, it attempts to map the buffer as read-only into the page table. If this mapping fails, the function clears the page table entries but does not properly manage the associated performance event state. This oversight leads to a reference count leak, disrupts virtual memory accounting, and causes an imbalance in event mapping notifications. The vulnerability has been fixed by reorganizing the buffer mapping process to ensure that any failures are properly cleaned up, restoring balance to the event management system.

Impact

The vulnerability could lead to memory management issues, including reference count leaks and corrupted virtual memory accounting, which could disrupt the normal operation of performance monitoring events.

Remediation

Users can upgrade to the latest version of the Linux kernel to address this vulnerability. The specific commit that resolves the issue is available in the Linux kernel stable tree.