NFSD: Prevent lock owner use-after-free during client teardown
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent lock owner use-after-free during client teardown __destroy_client() releases a client's open owners, but a lock owner whose only reference is a blocked lock (nbl) stays on cl_ownerstr_hashtbl. client_has_state() does not count a bare owner, so DESTROY_CLIENTID can reach __destroy_client() with such owners present. __destroy_client() then walks the table, calling remove_blocked_locks() on each owner without a reference. Freeing a blocked lock drops the owner reference held via flc_owner. The per-net laundromat reaps blocked locks from nn->blocked_locks_lru independently of client state. The two paths share blocked_locks_lock only for the list splice, not the owner's lifetime. The laundromat therefore frees the owner as __destroy_client() dereferences it, a NULL dereference in remove_blocked_locks(). nfsd4_release_lockowner() holds a reference across the same call; __destroy_client() does not. Hold cl_lock across the walk, taking a reference and unhashing each owner, then drop it before remove_blocked_locks() and nfs4_put_stateowner(), which take blocked_locks_lock and cl_lock.
CVE-2026-89662
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-89662
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
"lessThan": "42d7954b0a1907d4ef122aef94561952a033cdc3",
"versionType": "git"
},
{
"status": "affected",
"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
"lessThan": "bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a",
"versionType": "git"
},
{
"status": "affected",
"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
"lessThan": "b8bad5a11416b26cc7fd4b18fba46d75ff636558",
"versionType": "git"
},
{
"status": "affected",
"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
"lessThan": "1ce74d1b7770e69735e8f8e509807af4ff9c8ee7",
"versionType": "git"
},
{
"status": "affected",
"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
"lessThan": "a6ead6fff3a7d03e49845f048f7000a2e0d34431",
"versionType": "git"
},
{
"status": "affected",
"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
"lessThan": "4804c58f73a80d12df1de323bf97a164f6ee8743",
"versionType": "git"
},
{
"status": "affected",
"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
"lessThan": "8cf4ff0a7c083dd5e0067f517d63979b74b66649",
"versionType": "git"
},
{
"status": "affected",
"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
"lessThan": "5e2fa29d223a9a1e6a948e40b109d09081d1decd",
"versionType": "git"
},
{
"status": "affected",
"version": "e294c4c2d33b7307a89cdf31bec08a112d6a9297",
"versionType": "git"
},
{
"status": "affected",
"version": "797bfd05d4040fbf766198b3cfcc1838002cc890",
"versionType": "git"
},
{
"status": "affected",
"version": "0f44e9da465ea259b6c9f31a627f3c50a16e1679",
"versionType": "git"
},
{
"status": "affected",
"version": "4.9.91",
"lessThan": "4.10",
"versionType": "semver"
},
{
"status": "affected",
"version": "4.14.31",
"lessThan": "4.15",
"versionType": "semver"
},
{
"status": "affected",
"version": "4.15.14",
"lessThan": "4.16",
"versionType": "semver"
}
],
"programFiles": [
"fs/nfsd/nfs4state.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.16"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.16",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/nfsd/nfs4state.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89662
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #35152 · Revision 1
- Added to Heist Feed
- Publisher date