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 unsigned int rtnl_dev_combine_flags(const struct net_device *dev,
					   const struct ifinfomsg *ifm)
{
	unsigned int flags = ifm->ifi_flags;

	/* bugwards compatibility: ifi_change == 0 is treated as ~0 */
	if (ifm->ifi_change)
		flags = (flags & ifm->ifi_change) |
			(rtnl_dev_get_flags(dev) & ~ifm->ifi_change);

	return flags;
}

static unsigned int rtnl_dev_combine_flags(const struct net_device *dev,
					   const struct ifinfomsg *ifm)
{
	unsigned int flags = ifm->ifi_flags;

	/* bugwards compatibility: ifi_change == 0 is treated as ~0 */
	if (ifm->ifi_change)
		flags = (flags & ifm->ifi_change) |
			(rtnl_dev_get_flags(dev) & ~ifm->ifi_change);

	return flags;
}
