Bluetooth: HCI - Fix info leak via getsockname()

The HCI code fails to initialize the hci_channel member of struct
sockaddr_hci and that for leaks two bytes kernel stack via the
getsockname() syscall. Initialize hci_channel with 0 to avoid the
info leak.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bluetooth/hci_sock.c

@@ -694,6 +694,7 @@ static int hci_sock_getname(struct socket *sock, struct sockaddr *addr,
 	*addr_len = sizeof(*haddr);
 	haddr->hci_family = AF_BLUETOOTH;
 	haddr->hci_dev    = hdev->id;
+	haddr->hci_channel= 0;
 
 	release_sock(sk);
 	return 0;