netdev - Re: [RFC] sctp/tcp: Question -- ICMPv4 length check (not) redundant?

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Message-Id: <20080725.213857.160776686.davem@davemloft.net>
Date:	Fri, 25 Jul 2008 21:38:57 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	vladislav.yasevich@...com
Cc:	gerrit@....abdn.ac.uk, netdev@...r.kernel.org
Subject: Re: [RFC] sctp/tcp: Question -- ICMPv4 length check (not)
 redundant?

From: Vlad Yasevich <vladislav.yasevich@...com>
Date: Fri, 25 Jul 2008 22:15:33 -0400

> Gerrit Renker wrote:
> >  * icmp_unreach() in net/ipv4/icmp.c already has this test:
> > 
> > 	/* Checkin full IP header plus 8 bytes of protocol to
> > 	 * avoid additional coding at protocol handlers.
> > 	 */
> >         if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
> >                 goto out;

I just noticed that this won't bump the ICMP MIB counter.

The ICMP code will only bump the counter if the IP header isn't there,
or has a bogus header length.

But it is clear in the callers that the intention is (or was) to bump
the counter if the 8 bytes of post IP header bits are not there.
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