CVE-2026-64300

Summary

In the Linux kernel, the following vulnerability has been resolved:

perf/aux: Fix page UAF in map_range()

map_range() reads rb->aux_pages[], rb->aux_nr_pages and rb->aux_pgoff via perf_mmap_to_page() while holding only event->mmap_mutex. Those fields are serialized by rb->aux_mutex, and mmap_mutex is per event.

Thus, two events sharing one rb via PERF_EVENT_IOC_SET_OUTPUT can race rb_alloc_aux() with map_range(), leading to a page-UAF scenario as follows:

CPU 0 CPU 1 ===== ===== rb_alloc_aux() map_range() [1]: allocate rb->aux_pages[0] [2]: rb->aux_nr_pages++ [3]: perf_mmap_to_page() returns rb->aux_pages[0] [4]: map it as VM_PFNMAP [5]: rb->aux_pgoff = 1

munmap the page [6]: free rb->aux_pages[0]

Pages mapped as VM_PFNMAP have no refcount protection, so CPU 1 holds a mapping to a freed physical frame.

Fix this by taking rb->aux_mutex across the page walk in map_range().

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/c8b7e113f7b61eef2f017e6329c27c2331058c5a
• https://git.kernel.org/stable/c/0cff05bd2186020f8706233e261016d149cc24db
• https://git.kernel.org/stable/c/5948aaf64f81f217a25dcc2bf6c0779bca19566c

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