NFSD: Prevent client use-after-free during admin state revocation

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89660
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:52 UTC
Updated2026-09-11 20:19:52 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during admin state revocation A stateid holds only a bare pointer to its nfs4_client; a stateid reference does not pin it. The client survives only because __destroy_client() drains its stateids before free_client() runs. nfsd4_revoke_states() drops nn->client_lock across revoke_one_stid(), which dereferences the client to revoke a stateid and read clp->cl_minorversion. A teardown racing the dropped lock can free the client first. Pinning cl_rpc_users under client_lock blocks the DESTROY_CLIENTID and EXCHANGE_ID teardown, which refuses while cl_rpc_users is non-zero. force_expire_client() ignores it: once its wait for cl_rpc_users to reach zero has passed, a later pin goes unnoticed. Under client_lock, skip a client whose cl_time is already zero -- force_expire_client() clears it there before waiting -- otherwise pin cl_rpc_users before dropping the lock. The walk then either sees the expiry and skips, or pins in time for that wait to cover the revoke.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc 549bd9868e9d77b07ea94870940d64342829c6ad git Not specified
CNA Linux Linux affected 1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc bf1f948691523282cc4905bc6cd325e0c0b49e6a git Not specified
CNA Linux Linux affected 1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc e270e5a0778e5bff852c8862ce9576ce70359393 git Not specified
CNA Linux Linux affected 6.9 Not specified
CNA Linux Linux unaffected 6.9 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/bf1f948691523282cc4905bc6cd325e0c0b49e6a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e270e5a0778e5bff852c8862ce9576ce70359393 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/549bd9868e9d77b07ea94870940d64342829c6ad 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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