Bug 2492376 (CVE-2026-53129)

Summary: CVE-2026-53129 kernel: fs/mbcache: cancel shrink work before destroying the cache
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2026-06-24 18:08:42 UTC 
In the Linux kernel, the following vulnerability has been resolved:

fs/mbcache: cancel shrink work before destroying the cache

mb_cache_destroy() calls shrinker_free() and then frees all cache
entries and the cache itself, but it does not cancel the pending
c_shrink_work work item first.

If mb_cache_entry_create() schedules c_shrink_work via schedule_work()
and the work item is still pending or running when mb_cache_destroy()
runs, mb_cache_shrink_worker() will access the cache after its memory
has been freed, causing a use-after-free.

This is only reachable by a privileged user (root or CAP_SYS_ADMIN)
who can trigger the last put of a mounted ext2/ext4/ocfs2 filesystem.

Cancel the work item with cancel_work_sync() before calling
shrinker_free(), ensuring the worker has finished and will not be
rescheduled before the cache is torn down.
Comment 1 Mauro Matteo Cascella 2026-06-24 18:25:53 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062418-CVE-2026-53129-781c@gregkh/T