iucv: Fix missing msg_namelen update in iucv_sock_recvmsg()

The current code does not fill the msg_name member in case it is set.
It also does not set the msg_namelen member to 0 and therefore makes
net/socket.c leak the local, uninitialized sockaddr_storage variable
to userland -- 128 bytes of kernel stack memory.

Fix that by simply setting msg_namelen to 0 as obviously nobody cared
about iucv_sock_recvmsg() not filling the msg_name in case it was set.

Cc: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static int afiucv_netdev_event(struct notifier_block *this,
			       unsigned long event, void *ptr)
{
	struct net_device *event_dev = (struct net_device *)ptr;
	struct sock *sk;
	struct iucv_sock *iucv;

	switch (event) {
	case NETDEV_REBOOT:
	case NETDEV_GOING_DOWN:
		sk_for_each(sk, &iucv_sk_list.head) {
			iucv = iucv_sk(sk);
			if ((iucv->hs_dev == event_dev) &&
			    (sk->sk_state == IUCV_CONNECTED)) {
				if (event == NETDEV_GOING_DOWN)
					iucv_send_ctrl(sk, AF_IUCV_FLAG_FIN);
				sk->sk_state = IUCV_DISCONN;
				sk->sk_state_change(sk);
			}
		}
		break;
	case NETDEV_DOWN:
	case NETDEV_UNREGISTER:
	default:
		break;
	}
	return NOTIFY_DONE;
}

static int afiucv_netdev_event(struct notifier_block *this,
			       unsigned long event, void *ptr)
{
	struct net_device *event_dev = (struct net_device *)ptr;
	struct sock *sk;
	struct iucv_sock *iucv;

	switch (event) {
	case NETDEV_REBOOT:
	case NETDEV_GOING_DOWN:
		sk_for_each(sk, &iucv_sk_list.head) {
			iucv = iucv_sk(sk);
			if ((iucv->hs_dev == event_dev) &&
			    (sk->sk_state == IUCV_CONNECTED)) {
				if (event == NETDEV_GOING_DOWN)
					iucv_send_ctrl(sk, AF_IUCV_FLAG_FIN);
				sk->sk_state = IUCV_DISCONN;
				sk->sk_state_change(sk);
			}
		}
		break;
	case NETDEV_DOWN:
	case NETDEV_UNREGISTER:
	default:
		break;
	}
	return NOTIFY_DONE;
}
