CVE-2026-89686

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke nfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding fi_lock when the parent stateid is a delegation. A concurrent delegation revoke via the laundromat can clear fi_deleg_file under fi_lock, causing nfsd_file_get() to return NULL and triggering the BUG_ON. This race is client-reachable: two NFS clients can trigger it by having one hold a delegation while another opens the same file to force a recall. When the first client doesn't respond to the recall, the laundromat revokes it. A concurrent LAYOUTGET from any client using the delegation stateid hits the race window. Fix this by taking fi_lock around the fi_deleg_file read in the SC_TYPE_DELEG path, matching the locking discipline of the find_any_file() arm, and replacing the BUG_ON with a graceful error return that cleans up the partially-initialized layout stateid.

CVSS v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://git.kernel.org/stable/c/607a56fea772c1f4f4989d8e255dd4f7192d9604
https://git.kernel.org/stable/c/97bda8b4284d90897a1f1922e5082ff9e35d7c7e
https://git.kernel.org/stable/c/c517f27498757e616d2a8fe6d16caad1fee422e6
https://git.kernel.org/stable/c/ca94ba36172046be6a694a7986f6931e47ed4d51

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-11 20:19

Updated : 2026-09-13 07:17

NVD link : CVE-2026-89686

Mitre link : CVE-2026-89686

CVE.ORG link : CVE-2026-89686

JSON object : View

Products Affected

No product.

CWE

No CWE.

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