NFSD: Prevent client use-after-free during delegation revoke

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89659
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:52 UTC
Updated2026-10-16 20:18:25 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during delegation revoke A delegation stateid holds only a bare pointer to its owning nfs4_client and does not keep it alive. The client survives its stateids only because __destroy_client() drains cl_delegations and cl_revoked before free_client() runs. nfs4_laundromat() breaks that invariant: it unhashes an expired delegation from cl_delegations, drops deleg_lock, then revoke_delegation() relinks it onto cl_revoked under cl_lock. In that window the delegation is on neither list, so client_has_state() can report no remaining state. Every teardown path first requires cl_rpc_users to be zero, but the laundromat holds no such reference. A client whose recalled delegation has just timed out can therefore reach free_client() while revoke_delegation() is still about to dereference cl_lock, a use-after-free. Pin the client with cl_rpc_users across the revoke so teardown blocks until it completes, then reap the delegation from cl_revoked. A client already expiring reaps its own, so skip it and leave the delegation on del_recall_lru.

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: 0.004500000 probability, percentile 0.384810000 (date 2026-09-22)

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 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54 0dd276b1324a5e08e83c6f675919946c9f0d61c9 git Not specified
CNA Linux Linux affected 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54 3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3 git Not specified
CNA Linux Linux affected 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54 2a9d637c2a8fd8ac29ad9b29f28d122ef75c1a56 git Not specified
CNA Linux Linux affected 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54 4683ca76b3b7e5808338491c6eb3c20e6b4894d5 git Not specified
CNA Linux Linux affected 3.10 Not specified
CNA Linux Linux unaffected 3.10 semver Not specified
CNA Linux Linux unaffected 6.12.111 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.51 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/0dd276b1324a5e08e83c6f675919946c9f0d61c9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4683ca76b3b7e5808338491c6eb3c20e6b4894d5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2a9d637c2a8fd8ac29ad9b29f28d122ef75c1a56 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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