CVE-2026-23248 (GCVE-0-2026-23248)

Vulnerability from cvelistv5 – Published: 2026-03-18 10:05 – Updated: 2026-04-13 06:03
VLAI?
Title
perf/core: Fix refcount bug and potential UAF in perf_mmap
Summary
In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix refcount bug and potential UAF in perf_mmap Syzkaller reported a refcount_t: addition on 0; use-after-free warning in perf_mmap. The issue is caused by a race condition between a failing mmap() setup and a concurrent mmap() on a dependent event (e.g., using output redirection). In perf_mmap(), the ring_buffer (rb) is allocated and assigned to event->rb with the mmap_mutex held. The mutex is then released to perform map_range(). If map_range() fails, perf_mmap_close() is called to clean up. However, since the mutex was dropped, another thread attaching to this event (via inherited events or output redirection) can acquire the mutex, observe the valid event->rb pointer, and attempt to increment its reference count. If the cleanup path has already dropped the reference count to zero, this results in a use-after-free or refcount saturation warning. Fix this by extending the scope of mmap_mutex to cover the map_range() call. This ensures that the ring buffer initialization and mapping (or cleanup on failure) happens atomically effectively, preventing other threads from accessing a half-initialized or dying ring buffer.
Severity ?
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < c27dea9f50ed525facb62ef647dddc4722456e07 (git)
Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < ac7ecb65af170a7fc193e7bd8be15dac84ec6a56 (git)
Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < 77de62ad3de3967818c3dbe656b7336ebee461d2 (git)
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    Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.7 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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