NFS: Return a delegation the client fails to record

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Summary

CVECVE-2026-90234
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:17:19 UTC
Updated2026-09-17 17:17:19 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: NFS: Return a delegation the client fails to record When an NFS server grants a delegation in an OPEN reply, nfs_inode_set_delegation() records it on the client. However, three of its error flows return without sending DELEGRETURN. A delegation can be relinquished only by DELEGRETURN (RFC 8881 Section 20.2.4), so dropping one silently leaves the server believing the client still holds it. If the server happens to recall that delegation, the client answers CB_RECALL with NFS4ERR_BADHANDLE because it has no record of the stateid. The server revokes the delegation and moves it onto its cl_revoked list, because the client never sends the FREE_STATEID that would drain it. Every subsequent SEQUENCE reply then carries SEQ4_STATUS_RECALLABLE_STATE_REVOKED, and the client's state manager loops issuing TEST_STATEID across its delegations without ever clearing the condition. The window is easy to reach now that a server offers a write delegation on any write OPEN: a delegation recalled for one opener races a re-open that the server answers with a fresh write delegation. Instead of dropping it, hand the delegation back during these error flows.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ade04647dd56881e285983af3db702d56ee97e86 92533e49fe3c455088657b862cf3562260c0ce25 git Not specified
CNA Linux Linux affected ade04647dd56881e285983af3db702d56ee97e86 220af23d863995091f0edeb1e6aa0945b3db8b37 git Not specified
CNA Linux Linux affected 4.0 Not specified
CNA Linux Linux unaffected 4.0 semver Not specified
CNA Linux Linux unaffected 7.2.6 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/92533e49fe3c455088657b862cf3562260c0ce25 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/220af23d863995091f0edeb1e6aa0945b3db8b37 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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