In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: serialize...

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.