VSOCK: Fix missing msg_namelen update in vsock_stream_recvmsg()

The code misses to update 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.

Cc: Andy King <acking@vmware.com>
Cc: Dmitry Torokhov <dtor@vmware.com>
Cc: George Zhang <georgezhang@vmware.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
void vsock_core_exit(void)
{
	mutex_lock(&vsock_register_mutex);

	misc_deregister(&vsock_device);
	sock_unregister(AF_VSOCK);
	proto_unregister(&vsock_proto);

	/* We do not want the assignment below re-ordered. */
	mb();
	transport = NULL;

	mutex_unlock(&vsock_register_mutex);
}

void vsock_core_exit(void)
{
	mutex_lock(&vsock_register_mutex);

	misc_deregister(&vsock_device);
	sock_unregister(AF_VSOCK);
	proto_unregister(&vsock_proto);

	/* We do not want the assignment below re-ordered. */
	mb();
	transport = NULL;

	mutex_unlock(&vsock_register_mutex);
}
