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CVE PROGRAM SOURCE RECORD9.8 Critical

CVE-2026-89662

NFSD: Prevent lock owner use-after-free during client teardown

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
Linux

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 68ef3bc3166468678d5e1fdd216628c35bd1186f to < 42d7954b0a1907d4ef122aef94561952a033cdc3affected
  • 68ef3bc3166468678d5e1fdd216628c35bd1186f to < bb38ff8b4dafbbd1781ad37cd96722fdf2cd972aaffected
  • 68ef3bc3166468678d5e1fdd216628c35bd1186f to < b8bad5a11416b26cc7fd4b18fba46d75ff636558affected
  • 68ef3bc3166468678d5e1fdd216628c35bd1186f to < 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7affected
  • 68ef3bc3166468678d5e1fdd216628c35bd1186f to < a6ead6fff3a7d03e49845f048f7000a2e0d34431affected
  • 68ef3bc3166468678d5e1fdd216628c35bd1186f to < 4804c58f73a80d12df1de323bf97a164f6ee8743affected
  • 68ef3bc3166468678d5e1fdd216628c35bd1186f to < 8cf4ff0a7c083dd5e0067f517d63979b74b66649affected
  • 68ef3bc3166468678d5e1fdd216628c35bd1186f to < 5e2fa29d223a9a1e6a948e40b109d09081d1decdaffected
  • e294c4c2d33b7307a89cdf31bec08a112d6a9297affected
  • 797bfd05d4040fbf766198b3cfcc1838002cc890affected
  • 0f44e9da465ea259b6c9f31a627f3c50a16e1679affected
  • 4.9.91 to < 4.10affected
  • 4.14.31 to < 4.15affected
  • 4.15.14 to < 4.16affected

Linux Linux

Default version status: affected

  • 4.16affected
  • 0 to < 4.16unaffected
  • 5.10.270 to ≤ 5.10.*unaffected
  • 5.15.221 to ≤ 5.15.*unaffected
  • 6.1.188 to ≤ 6.1.*unaffected
  • 6.6.157 to ≤ 6.6.*unaffected
  • 6.12.109 to ≤ 6.12.*unaffected
  • 6.18.50 to ≤ 6.18.*unaffected
  • 7.2.4 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References