CVE-2026-90037NFSD: Prevent client use-after-free during close_lru reaping

Official description

In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during close_lru reaping An nfs4_openowner left on nn->close_lru after its final CLOSE keeps its last closed stateid in oo_last_closed_stid, holding only a raw pointer to its nfs4_client. The laundromat reaps timed-out entries, drops nn->client_lock, and calls nfs4_put_stid(), which dereferences the client through cl_lock. Nothing pins the client across that window, so a concurrent force_expire_client() can free it and nfs4_put_stid() reads freed memory. __destroy_client() hits the same race, walking clp->cl_openowners without cl_lock. Pin the client with cl_rpc_users before dropping client_lock, and skip clients already expiring. __destroy_client() then cleans up its own close_lru entries through release_last_closed_stateid(), so teardown no longer races the laundromat.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/1d721729762a413015864b2a56d7fb86fb8efa9f
• https://git.kernel.org/stable/c/adc34b5df5c5d87043cb500b0867fc1c4ad0117e
• https://git.kernel.org/stable/c/0763482227822f7343557f086afc382086d56c4c
• https://git.kernel.org/stable/c/83dd59ac1c3455c2c7d8ddb582d980a13199b9b3
• https://git.kernel.org/stable/c/e57a9ed34ea8c17e831de59b8f1a6b2d80d347a1
• https://git.kernel.org/stable/c/2330b788d732f43668b965b3105b37ceb276dfea