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>
int __rtnl_link_register(struct rtnl_link_ops *ops)
{
	if (rtnl_link_ops_get(ops->kind))
		return -EEXIST;

	if (!ops->dellink)
		ops->dellink = unregister_netdevice_queue;

	list_add_tail(&ops->list, &link_ops);
	return 0;
}

int __rtnl_link_register(struct rtnl_link_ops *ops)
{
	if (rtnl_link_ops_get(ops->kind))
		return -EEXIST;

	if (!ops->dellink)
		ops->dellink = unregister_netdevice_queue;

	list_add_tail(&ops->list, &link_ops);
	return 0;
}
