Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during blocked-lock reaping A bare lock owner -- its only remaining reference a blocked lock on nn->blocked_locks_lru -- holds a raw pointer to its nfs4_client but no reference keeping the client alive. When the per-net laundromat reaps such a lock, freeing the nbl drops the owner reference held through flc_owner, and the final nfs4_put_stateowner() takes the client's cl_lock. Because the laundromat detaches the nbl first, __destroy_client() no longer finds it, so a concurrent force_expire_client() can free the client before nfs4_put_stateowner() runs, dereferencing cl_lock in freed memory. Pin the client with cl_rpc_users before dropping nn->blocked_locks_lock, and skip clients already expiring, whose blocked locks __destroy_client() frees while holding an owner reference. Take nn->client_lock outside nn->blocked_locks_lock. Every other site holds nn->blocked_locks_lock as a leaf, acquiring no further lock, so placing nn->client_lock outside it cannot form a lock-order cycle.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b before 0d53a47c913d0bce3b5ec35c28cbcca4d015f33d; affected 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b before 7081224a59a0ca4edcd62c068588f4d900199a18; affected 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b before cd489b03587378645fe0d20142a33f1ed60bac98; affected 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b before 6fedb2eaff77554ca7a0deffd2e8bc0d6e8b38b0; affected 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b before 9026932ac8be4d0ae01db47f23619a98cc57b671 |
| Linux / Linux | affected 4.9; unaffected 0 before 4.9; unaffected 6.6.160 through 6.6.*; unaffected 6.12.111 through 6.12.*; unaffected 6.18.51 through 6.18.*; unaffected 7.2.5 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/0d53a47c913d0bce3b5ec35c28cbcca4d015f33d
- https://git.kernel.org/stable/c/7081224a59a0ca4edcd62c068588f4d900199a18
- https://git.kernel.org/stable/c/cd489b03587378645fe0d20142a33f1ed60bac98
- https://git.kernel.org/stable/c/6fedb2eaff77554ca7a0deffd2e8bc0d6e8b38b0
- https://git.kernel.org/stable/c/9026932ac8be4d0ae01db47f23619a98cc57b671