CVE-2026-64300 in Linux
Riassunto
di MITRE • 25/07/2026
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().
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