NFSD: Prevent lock owner use-after-free during client teardown

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89662
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:52 UTC
Updated2026-09-13 07:17:31 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.002000000 probability, percentile 0.099730000 (date 2026-09-12)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 68ef3bc3166468678d5e1fdd216628c35bd1186f a6ead6fff3a7d03e49845f048f7000a2e0d34431 git Not specified
CNA Linux Linux affected 68ef3bc3166468678d5e1fdd216628c35bd1186f 4804c58f73a80d12df1de323bf97a164f6ee8743 git Not specified
CNA Linux Linux affected 68ef3bc3166468678d5e1fdd216628c35bd1186f 8cf4ff0a7c083dd5e0067f517d63979b74b66649 git Not specified
CNA Linux Linux affected 68ef3bc3166468678d5e1fdd216628c35bd1186f 5e2fa29d223a9a1e6a948e40b109d09081d1decd git Not specified
CNA Linux Linux affected e294c4c2d33b7307a89cdf31bec08a112d6a9297 git Not specified
CNA Linux Linux affected 797bfd05d4040fbf766198b3cfcc1838002cc890 git Not specified
CNA Linux Linux affected 0f44e9da465ea259b6c9f31a627f3c50a16e1679 git Not specified
CNA Linux Linux affected 4.9.91 4.10 semver Not specified
CNA Linux Linux affected 4.14.31 4.15 semver Not specified
CNA Linux Linux affected 4.15.14 4.16 semver Not specified
CNA Linux Linux affected 4.16 Not specified
CNA Linux Linux unaffected 4.16 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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