Bug 2532183 (CVE-2026-89485)

Summary: CVE-2026-89485 kernel: lockd: pin next file across nlm_inspect_file lock-drop
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the `lockd` component of the Linux kernel. This use-after-free vulnerability occurs in the `nlm_traverse_files()` function when a file's memory is prematurely released while an iterator still holds a pointer to it. A remote attacker could potentially exploit this to cause system instability or a denial of service (DoS) by triggering a concurrent file release during a specific unlock window.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 21:10:47 UTC 
In the Linux kernel, the following vulnerability has been resolved:

lockd: pin next file across nlm_inspect_file lock-drop

nlm_traverse_files() pins the current file with f_count++ across
a mutex_unlock for nlm_inspect_file(), but nothing pins the saved
next pointer.  A concurrent nlm_release_file() can kfree the next
file during the unlock window, and the iterator dereferences freed
memory on the next loop step.

Pin both current and next before the lock-drop.  Advance by
swapping the pinned cursors at the end of each iteration so next
is always held alive across the unlock.

Always call nlm_file_release() after dropping the iteration pin,
regardless of whether the file matched the predicate.  Use
nlm_file_inuse(), which does a live walk of the inode lock list,
rather than the cached f_locks field, so skipped files that never
ran nlm_inspect_file() are evaluated correctly.

Because every file in a hash bucket is now pinned and released,
files skipped by the is_failover_file predicate that have no
locks, blocks, shares, or external references are deleted during
traversal.  The old code never evaluated skipped files for
cleanup.  The new behavior is intentional: such files are stale
and should not persist in the table.
Comment 1 Mauro Matteo Cascella 2026-09-18 10:07:39 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89485.mbox