Bluetooth: hci_qca: Use del_timer_sync() before freeing

While looking at a crash report on a timer list being corrupted, which
usually happens when a timer is freed while still active. This is
commonly triggered by code calling del_timer() instead of
del_timer_sync() just before freeing.

One possible culprit is the hci_qca driver, which does exactly that.

Eric mentioned that wake_retrans_timer could be rearmed via the work
queue, so also move the destruction of the work queue before
del_timer_sync().

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: stable@vger.kernel.org
Fixes: 0ff252c1 ("Bluetooth: hciuart: Add support QCA chipset for UART")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_qca.c

@@ -696,9 +696,9 @@ static int qca_close(struct hci_uart *hu)
 	skb_queue_purge(&qca->tx_wait_q);
 	skb_queue_purge(&qca->txq);
 	skb_queue_purge(&qca->rx_memdump_q);
-	del_timer(&qca->tx_idle_timer);
-	del_timer(&qca->wake_retrans_timer);
 	destroy_workqueue(qca->workqueue);
+	del_timer_sync(&qca->tx_idle_timer);
+	del_timer_sync(&qca->wake_retrans_timer);
 	qca->hu = NULL;
 
 	kfree_skb(qca->rx_skb);