VSOCK: vmci - fix possible info leak in vmci_transport_dgram_dequeue()

In case we received no data on the call to skb_recv_datagram(), i.e.
skb->data is NULL, vmci_transport_dgram_dequeue() will return with 0
without updating msg_namelen leading to net/socket.c leaking the local,
uninitialized sockaddr_storage variable to userland -- 128 bytes of
kernel stack memory.

Fix this by moving the already existing msg_namelen assignment a few
lines above.

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>
static bool vmci_transport_stream_allow(u32 cid, u32 port)
{
	static const u32 non_socket_contexts[] = {
		VMADDR_CID_HYPERVISOR,
		VMADDR_CID_RESERVED,
	};
	int i;

	BUILD_BUG_ON(sizeof(cid) != sizeof(*non_socket_contexts));

	for (i = 0; i < ARRAY_SIZE(non_socket_contexts); i++) {
		if (cid == non_socket_contexts[i])
			return false;
	}

	return true;
}

static bool vmci_transport_stream_allow(u32 cid, u32 port)
{
	static const u32 non_socket_contexts[] = {
		VMADDR_CID_HYPERVISOR,
		VMADDR_CID_RESERVED,
	};
	int i;

	BUILD_BUG_ON(sizeof(cid) != sizeof(*non_socket_contexts));

	for (i = 0; i < ARRAY_SIZE(non_socket_contexts); i++) {
		if (cid == non_socket_contexts[i])
			return false;
	}

	return true;
}
