Bluetooth: hci_bcsp: Fix memory leak in rx_skb

Syzkaller found that it is possible to provoke a memory leak by
never freeing rx_skb in struct bcsp_struct.

Fix by freeing in bcsp_close()
Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+98162c885993b72f19c4@syzkaller.appspotmail.com
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_bcsp.c

@@ -744,6 +744,11 @@ static int bcsp_close(struct hci_uart *hu)
 	skb_queue_purge(&bcsp->rel);
 	skb_queue_purge(&bcsp->unrel);
 
+	if (bcsp->rx_skb) {
+		kfree_skb(bcsp->rx_skb);
+		bcsp->rx_skb = NULL;
+	}
+
 	kfree(bcsp);
 	return 0;
 }