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 iucv_sock_getname(struct socket *sock, struct sockaddr *addr,
			     int *len, int peer)
{
	struct sockaddr_iucv *siucv = (struct sockaddr_iucv *) addr;
	struct sock *sk = sock->sk;
	struct iucv_sock *iucv = iucv_sk(sk);

	addr->sa_family = AF_IUCV;
	*len = sizeof(struct sockaddr_iucv);

	if (peer) {
		memcpy(siucv->siucv_user_id, iucv->dst_user_id, 8);
		memcpy(siucv->siucv_name, iucv->dst_name, 8);
	} else {
		memcpy(siucv->siucv_user_id, iucv->src_user_id, 8);
		memcpy(siucv->siucv_name, iucv->src_name, 8);
	}
	memset(&siucv->siucv_port, 0, sizeof(siucv->siucv_port));
	memset(&siucv->siucv_addr, 0, sizeof(siucv->siucv_addr));
	memset(&siucv->siucv_nodeid, 0, sizeof(siucv->siucv_nodeid));

	return 0;
}

static int iucv_sock_getname(struct socket *sock, struct sockaddr *addr,
			     int *len, int peer)
{
	struct sockaddr_iucv *siucv = (struct sockaddr_iucv *) addr;
	struct sock *sk = sock->sk;
	struct iucv_sock *iucv = iucv_sk(sk);

	addr->sa_family = AF_IUCV;
	*len = sizeof(struct sockaddr_iucv);

	if (peer) {
		memcpy(siucv->siucv_user_id, iucv->dst_user_id, 8);
		memcpy(siucv->siucv_name, iucv->dst_name, 8);
	} else {
		memcpy(siucv->siucv_user_id, iucv->src_user_id, 8);
		memcpy(siucv->siucv_name, iucv->src_name, 8);
	}
	memset(&siucv->siucv_port, 0, sizeof(siucv->siucv_port));
	memset(&siucv->siucv_addr, 0, sizeof(siucv->siucv_addr));
	memset(&siucv->siucv_nodeid, 0, sizeof(siucv->siucv_nodeid));

	return 0;
}
