Use After Free Affecting gfs2-kmp-default package, versions <6.12.0-160000.36.1


Severity

Recommended
0.0
high
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.12% (3rd percentile)

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  • Snyk IDSNYK-SLES1600-GFS2KMPDEFAULT-18344781
  • published28 Jul 2026
  • disclosed21 Jul 2026

Introduced: 21 Jul 2026

NewCVE-2026-23248  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade SLES:16.0.0 gfs2-kmp-default to version 6.12.0-160000.36.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream gfs2-kmp-default package and not the gfs2-kmp-default package as distributed by SLES. See How to fix? for SLES:16.0.0 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1