ip_fastforward() sanity check..

[James]

I seem to have a little concern in one specific early-sanity check in the
ip_fastforward() function of the latest 5.3 code base:

	/*
	 * Is first mbuf large enough for ip header and is header present?
	 */
	if (m->m_len < sizeof (struct ip) &&
	   (m = m_pullup(m, sizeof (struct ip))) == 0) {
		ipstat.ips_toosmall++;
		goto drop;
	}

Okay, if m_pullup() returns 0 due to failure, it already called m_freem(m) by
itself. But we have "goto drop;" after that, which is redundant, no?

I don't think this is a bit of issue in IPv4 implementation, but as obviously,
in IPv6 implementation, if calling 'goto drop' or redundant m_freem(m) in case
where m_pullup returns NULL/0, it may crash the kernel rock hard at 
m_tag_delete_chain in uipc_mbuf.c (even if you are checking 'if (m) m_freem(m)'
as remains are left over)

If any one has any comments, please let me know. If this is not a concern
please disregard my rant and excuse me for waste of time :)

Thanks,
-J

-- 
James Jun                                            TowardEX Technologies, Inc.
Technical Lead                       IPv4 and Native IPv6 Colocation, Bandwidth,
james at towardex.com             and Web Hosting Services in the Metro Boston area
cell: 1(978)-394-2867           web: http://www.towardex.com , noc: www.twdx.net