CVE-2026-74537

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: ISO: hold sk properly in iso_conn_ready

sk deref in iso_conn_ready must be done either under conn->lock, or holding a refcount, to avoid concurrent close. conn->sk is currently accessed without either:

[Task 1]            [Task 2]
                    iso_sock_release
iso_conn_ready
  sk = conn->sk
                      lock_sock(sk)
                        conn->sk = NULL
  lock_sock(sk)
                      release_sock(sk)
                      iso_sock_kill(sk)
   UAF on sk deref

Fix possible UAF by holding sk refcount in iso_conn_ready(). Also recheck after lock_sock that the socket is still valid. Adjust locking so conn->sk is cleared only under lock_sock.