GHSA-WCCQ-X362-CG9J
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32In 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.
{
"affected": [],
"aliases": [
"CVE-2026-89485"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:30Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nlockd: pin next file across nlm_inspect_file lock-drop\n\nnlm_traverse_files() pins the current file with f_count++ across\na mutex_unlock for nlm_inspect_file(), but nothing pins the saved\nnext pointer. A concurrent nlm_release_file() can kfree the next\nfile during the unlock window, and the iterator dereferences freed\nmemory on the next loop step.\n\nPin both current and next before the lock-drop. Advance by\nswapping the pinned cursors at the end of each iteration so next\nis always held alive across the unlock.\n\nAlways call nlm_file_release() after dropping the iteration pin,\nregardless of whether the file matched the predicate. Use\nnlm_file_inuse(), which does a live walk of the inode lock list,\nrather than the cached f_locks field, so skipped files that never\nran nlm_inspect_file() are evaluated correctly.\n\nBecause every file in a hash bucket is now pinned and released,\nfiles skipped by the is_failover_file predicate that have no\nlocks, blocks, shares, or external references are deleted during\ntraversal. The old code never evaluated skipped files for\ncleanup. The new behavior is intentional: such files are stale\nand should not persist in the table.",
"id": "GHSA-wccq-x362-cg9j",
"modified": "2026-09-14T15:32:26Z",
"published": "2026-09-11T21:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89485"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/08a455f87b14c7ff22ae3fdadda62a796a3a5572"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/350087f231c11efcd288c310707c40eab63ca583"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/41f0a6d31615fcae261bf28a0aa50050dc93a401"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/526c49cff3f72c3ec74752016380c7567040581b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/550c19222c7132c888e23c9d89079ba1c9bc4cca"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c24bdb7df2f34bdc38ca8a73796f5acb40f1830c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e3c413f789eaf0170275c7eba523ead73d963f30"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e999a88133654c6dfc68487fb49da5f20dfa2d4f"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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