Bluetooth: hci_h5: close serdev device and free hu in h5_close

When h5_close() gets called, the memory allocated for the hu gets
freed only if hu->serdev doesn't exist. This leads to a memory leak.
So when h5_close() is requested, close the serdev device instance and
free the memory allocated to the hu entirely instead.

Fixes: https://syzkaller.appspot.com/bug?extid=6ce141c55b2f7aafd1c4
Reported-by: syzbot+6ce141c55b2f7aafd1c4@syzkaller.appspotmail.com
Tested-by: syzbot+6ce141c55b2f7aafd1c4@syzkaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_h5.c

@@ -248,8 +248,12 @@ static int h5_close(struct hci_uart *hu)
 	if (h5->vnd && h5->vnd->close)
 		h5->vnd->close(h5);
 
-	if (!hu->serdev)
-		kfree(h5);
+	if (hu->serdev)
+		serdev_device_close(hu->serdev);
+
+	kfree_skb(h5->rx_skb);
+	kfree(h5);
+	h5 = NULL;
 
 	return 0;
 }