Bluetooth: fix init and cleanup of sco_conn.timeout_work

Before freeing struct sco_conn, all delayed timeout work should be
cancelled. Otherwise, sco_sock_timeout could potentially use the
sco_conn after it has been freed.

Additionally, sco_conn.timeout_work should be initialized when the
connection is allocated, not when the channel is added. This is
because an sco_conn can create channels with multiple sockets over its
lifetime, which happens if sockets are released but the connection
isn't deleted.

Fixes: ba316be1b6a0 ("Bluetooth: schedule SCO timeouts with delayed_work")
Signed-off-by: Desmond Cheong Zhi Xi <[e-mail]>
Signed-off-by: Luiz Augusto von Dentz <[e-mail]>

net/bluetooth/sco.c

···
 		return NULL;
 
 	spin_lock_init(&conn->lock);
+	INIT_DELAYED_WORK(&conn->timeout_work, sco_sock_timeout);
 
 	hcon->sco_data = conn;
 	conn->hcon = hcon;
···
 		sco_chan_del(sk, err);
 		release_sock(sk);
 		sock_put(sk);
-
-		/* Ensure no more work items will run before freeing conn. */
-		cancel_delayed_work_sync(&conn->timeout_work);
 	}
+
+	/* Ensure no more work items will run before freeing conn. */
+	cancel_delayed_work_sync(&conn->timeout_work);
 
 	hcon->sco_data = NULL;
 	kfree(conn);
···
 
 	sco_pi(sk)->conn = conn;
 	conn->sk = sk;
-
-	INIT_DELAYED_WORK(&conn->timeout_work, sco_sock_timeout);
 
 	if (parent)
 		bt_accept_enqueue(parent, sk, true);