rtnl: fix info leak on RTM_GETLINK request for VF devices

Initialize the mac address buffer with 0 as the driver specific function
will probably not fill the whole buffer. In fact, all in-kernel drivers
fill only ETH_ALEN of the MAX_ADDR_LEN bytes, i.e. 6 of the 32 possible
bytes. Therefore we currently leak 26 bytes of stack memory to userland
via the netlink interface.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static rtnl_calcit_func rtnl_get_calcit(int protocol, int msgindex)
{
	struct rtnl_link *tab;

	if (protocol <= RTNL_FAMILY_MAX)
		tab = rtnl_msg_handlers[protocol];
	else
		tab = NULL;

	if (tab == NULL || tab[msgindex].calcit == NULL)
		tab = rtnl_msg_handlers[PF_UNSPEC];

	return tab[msgindex].calcit;
}

static rtnl_calcit_func rtnl_get_calcit(int protocol, int msgindex)
{
	struct rtnl_link *tab;

	if (protocol <= RTNL_FAMILY_MAX)
		tab = rtnl_msg_handlers[protocol];
	else
		tab = NULL;

	if (tab == NULL || tab[msgindex].calcit == NULL)
		tab = rtnl_msg_handlers[PF_UNSPEC];

	return tab[msgindex].calcit;
}
