In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: serialize iso_sock_clear_timer with socket lock iso_so

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:

 1if (!iso_pi(sk)->conn)
 2    return;
 3cancel_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:

 1CPU0                         CPU1
 2----                         ----
 3iso_sock_clear_timer()
 4  if (conn != NULL) ...      lock_sock(sk)
 5                               iso_chan_del()
 6                               iso_pi(sk)->conn = NULL
 7  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.