In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: ISO: serialize iso_sock_clear_timer with socket lock
iso_sock_close() calls iso_sock_clear_timer() before acquiring lock_sock(sk).
iso_sock_clear_timer() reads iso_pi(sk)->conn twice without the socket lock held:
if (!iso_pi(sk)->conn) return; cancel_delayed_work(&iso_pi(sk)->conn->timeout_work);
Concurrently, iso_conn_del() executes under lock_sock(sk) and calls iso_chan_del(), which sets iso_pi(sk)->conn to NULL and may result in the final reference to the connection being dropped:
CPU0 CPU1 ---- ---- iso_sock_clear_timer() if (conn != NULL) ... lock_sock(sk) iso_chan_del() iso_pi(sk)->conn = NULL cancel_delayed_work(conn) /* NULL deref or UAF */
iso_pi(sk)->conn is not stable across the unlock window, causing a NULL pointer dereference or use-after-free.
Serialize iso_sock_clear_timer() with the socket lock by moving it inside lock_sock()/release_sock(), matching the pattern used in iso_conn_del() and all other call sites.