Linux Kernel NFSD: Fix Use-After-Free in close_lru Reaping
CVE-2026-90037 Published on September 16, 2026
NFSD: Prevent client use-after-free during close_lru reaping
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.
Products Associated with CVE-2026-90037
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Affected Versions
Linux:- Version 217526e7ecc9f6f243e976772e81eab7ab986a4c and below 83dd59ac1c3455c2c7d8ddb582d980a13199b9b3 is affected.
- Version 217526e7ecc9f6f243e976772e81eab7ab986a4c and below e57a9ed34ea8c17e831de59b8f1a6b2d80d347a1 is affected.
- Version 217526e7ecc9f6f243e976772e81eab7ab986a4c and below 2330b788d732f43668b965b3105b37ceb276dfea is affected.
- Version 3.17 is affected.
- Before 3.17 is unaffected.
- Version 6.18.51, <= 6.18.* is unaffected.
- Version 7.2.5, <= 7.2.* is unaffected.
- Version 7.3-rc1, <= * is unaffected.