CVE-2026-90038NFSD: Prevent client use-after-free during export state revocation

Official description

In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during export state revocation nfsd4_revoke_export_states() has the same use-after-free as nfsd4_revoke_states(): it drops nn->client_lock across revoke_one_stid() and the following read of clp->cl_minorversion, but the stateid reference it holds does not pin the client. A teardown racing the dropped lock can free the client while revoke_one_stid() still dereferences it. exportfs -u drives this path through NFSD_CMD_UNLOCK_EXPORT, so an administrator removing an export can race a client expiry. Skip a client that is already expiring and otherwise pin it with cl_rpc_users under client_lock before dropping the lock, matching nfsd4_revoke_states().

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/c05ae58fe06ce2ac34312f649e71c3596bdde358
• https://git.kernel.org/stable/c/2108de53568a64936a0da3e04d85c35df98d3fb6