CVE-2026-89662
Description
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent lock owner use-after-free during client teardown __destroy_client() releases a client's open owners, but a lock owner whose only reference is a blocked lock (nbl) stays on cl_ownerstr_hashtbl. client_has_state() does not count a bare owner, so DESTROY_CLIENTID can reach __destroy_client() with such owners present. __destroy_client() then walks the table, calling remove_blocked_locks() on each owner without a reference. Freeing a blocked lock drops the owner reference held via flc_owner. The per-net laundromat reaps blocked locks from nn->blocked_locks_lru independently of client state. The two paths share blocked_locks_lock only for the list splice, not the owner's lifetime. The laundromat therefore frees the owner as __destroy_client() dereferences it, a NULL dereference in remove_blocked_locks(). nfsd4_release_lockowner() holds a reference across the same call; __destroy_client() does not. Hold cl_lock across the walk, taking a reference and unhashing each owner, then drop it before remove_blocked_locks() and nfs4_put_stateowner(), which take blocked_locks_lock and cl_lock.
How to fix
- Linux Linux42d7954b0a1907d4ef122aef94561952a033cdc3, bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a, b8bad5a11416b26cc7fd4b18fba46d75ff636558, 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7, a6ead6fff3a7d03e49845f048f7000a2e0d34431, 4804c58f73a80d12df1de323bf97a164f6ee8743, 8cf4ff0a7c083dd5e0067f517d63979b74b66649, 5e2fa29d223a9a1e6a948e40b109d09081d1decd, 4.10, 4.15, 4.16 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux Linux | 68ef3bc3166468678d5e1fdd216628c35bd1186f ≤ v < 42d7954b0a1907d4ef122aef94561952a033cdc3, 68ef3bc3166468678d5e1fdd216628c35bd1186f ≤ v < bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a, 68ef3bc3166468678d5e1fdd216628c35bd1186f ≤ v < b8bad5a11416b26cc7fd4b18fba46d75ff636558, 68ef3bc3166468678d5e1fdd216628c35bd1186f ≤ v < 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7, 68ef3bc3166468678d5e1fdd216628c35bd1186f ≤ v < a6ead6fff3a7d03e49845f048f7000a2e0d34431, 68ef3bc3166468678d5e1fdd216628c35bd1186f ≤ v < 4804c58f73a80d12df1de323bf97a164f6ee8743, 68ef3bc3166468678d5e1fdd216628c35bd1186f ≤ v < 8cf4ff0a7c083dd5e0067f517d63979b74b66649, 68ef3bc3166468678d5e1fdd216628c35bd1186f ≤ v < 5e2fa29d223a9a1e6a948e40b109d09081d1decd, e294c4c2d33b7307a89cdf31bec08a112d6a9297, 797bfd05d4040fbf766198b3cfcc1838002cc890, 0f44e9da465ea259b6c9f31a627f3c50a16e1679, 4.9.91 ≤ v < 4.10, 4.14.31 ≤ v < 4.15, 4.15.14 ≤ v < 4.16, 4.16 | 42d7954b0a1907d4ef122aef94561952a033cdc3, bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a, b8bad5a11416b26cc7fd4b18fba46d75ff636558, 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7, a6ead6fff3a7d03e49845f048f7000a2e0d34431, 4804c58f73a80d12df1de323bf97a164f6ee8743, 8cf4ff0a7c083dd5e0067f517d63979b74b66649, 5e2fa29d223a9a1e6a948e40b109d09081d1decd, 4.10, 4.15, 4.16 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.