irda: Fix missing msg_namelen update in irda_recvmsg_dgram()

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 irda_recvmsg_dgram() not filling the msg_name in case it was
set.

Cc: Samuel Ortiz <samuel@sortiz.org>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static void irda_destroy_socket(struct irda_sock *self)
{
	IRDA_DEBUG(2, "%s(%p)\n", __func__, self);

	/* Unregister with IrLMP */
	irlmp_unregister_client(self->ckey);
	irlmp_unregister_service(self->skey);

	/* Unregister with LM-IAS */
	if (self->ias_obj) {
		irias_delete_object(self->ias_obj);
		self->ias_obj = NULL;
	}

	if (self->iriap) {
		iriap_close(self->iriap);
		self->iriap = NULL;
	}

	if (self->tsap) {
		irttp_disconnect_request(self->tsap, NULL, P_NORMAL);
		irttp_close_tsap(self->tsap);
		self->tsap = NULL;
	}
#ifdef CONFIG_IRDA_ULTRA
	if (self->lsap) {
		irlmp_close_lsap(self->lsap);
		self->lsap = NULL;
	}
#endif /* CONFIG_IRDA_ULTRA */
}

static void irda_destroy_socket(struct irda_sock *self)
{
	IRDA_DEBUG(2, "%s(%p)\n", __func__, self);

	/* Unregister with IrLMP */
	irlmp_unregister_client(self->ckey);
	irlmp_unregister_service(self->skey);

	/* Unregister with LM-IAS */
	if (self->ias_obj) {
		irias_delete_object(self->ias_obj);
		self->ias_obj = NULL;
	}

	if (self->iriap) {
		iriap_close(self->iriap);
		self->iriap = NULL;
	}

	if (self->tsap) {
		irttp_disconnect_request(self->tsap, NULL, P_NORMAL);
		irttp_close_tsap(self->tsap);
		self->tsap = NULL;
	}
#ifdef CONFIG_IRDA_ULTRA
	if (self->lsap) {
		irlmp_close_lsap(self->lsap);
		self->lsap = NULL;
	}
#endif /* CONFIG_IRDA_ULTRA */
}
