GHSA-MCQC-FM6V-5H2R
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-13 09:32In the Linux kernel, the following vulnerability has been resolved:
nfsd: clear CALLBACK_RUNNING on failed delegation recall queue
nfsd_break_one_deleg() sets NFSD4_CALLBACK_RUNNING via test_and_set_bit at entry to serialize recall work, then calls nfsd4_run_cb() to queue the recall. When the queue attempt fails the refcount bump is undone, but the RUNNING bit is left set. The only site that clears the bit is nfsd41_destroy_cb() (fs/nfsd/nfs4callback.c), which runs from the workqueue and is therefore unreachable when nothing was queued.
The bit becomes a permanent latch on dp->dl_recall.cb_flags: every subsequent break_lease() on the same delegation hits the early-return guard in nfsd_break_one_deleg() and silently skips the recall, so the delegation is never broken and the conflicting open or lock stalls.
Fix by clearing NFSD4_CALLBACK_RUNNING on the !queued branch alongside the refcount_dec.
{
"affected": [],
"aliases": [
"CVE-2026-89692"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:56Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear CALLBACK_RUNNING on failed delegation recall queue\n\nnfsd_break_one_deleg() sets NFSD4_CALLBACK_RUNNING via test_and_set_bit\nat entry to serialize recall work, then calls nfsd4_run_cb() to queue\nthe recall. When the queue attempt fails the refcount bump is undone,\nbut the RUNNING bit is left set. The only site that clears the bit is\nnfsd41_destroy_cb() (fs/nfsd/nfs4callback.c), which runs from the\nworkqueue and is therefore unreachable when nothing was queued.\n\nThe bit becomes a permanent latch on dp-\u003edl_recall.cb_flags: every\nsubsequent break_lease() on the same delegation hits the early-return\nguard in nfsd_break_one_deleg() and silently skips the recall, so the\ndelegation is never broken and the conflicting open or lock stalls.\n\nFix by clearing NFSD4_CALLBACK_RUNNING on the !queued branch alongside\nthe refcount_dec.",
"id": "GHSA-mcqc-fm6v-5h2r",
"modified": "2026-09-13T09:32:27Z",
"published": "2026-09-11T21:31:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89692"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b137930ee52e3ef38915a3511d4c070463b63a32"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cb2d0c4d1b3d301d042ed61365eaa8cb0141a254"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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