netdev - [0/7] [PPP]: Fix shared/cloned/non-linear skb bugs (was: malformed captured packets)

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Date:	Fri, 31 Aug 2007 17:06:25 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	James Chapman <jchapman@...alix.com>,
	"David S. Miller" <davem@...emloft.net>,
	Michal Ostrowski <mostrows@...akeasy.net>,
	Paul Mackerras <paulus@...ba.org>
Cc:	Toralf Förster <toralf.foerster@....de>,
	netdev@...r.kernel.org
Subject: [0/7] [PPP]: Fix shared/cloned/non-linear skb bugs (was: malformed captured packets)

On Thu, Aug 30, 2007 at 09:51:31AM +0000, James Chapman wrote:
>
> The captured PPPoE stream seems to show incorrect data lengths in the
> PPPoE header for some captured PPPoE packets. The kernel's PPPoE
> datapath uses this length to extract the PPP frame and send it through
> to the ppp interface. Since your ppp stream is fine, the actual PPPoE
> header contents must be correct when it is parsed by the kernel PPPoE
> code. It seems more likely that this is a wireshark bug to me.

If he were using the kernel pppoe driver, then this is because
PPP filtering is writing over a cloned skb without copying it.

In fact, there seems to be quite a few bugs of this kind in
the various ppp*.c files.

Please try the following patches to see if they make a
difference.

I've audited ppp_generic.c and pppoe.c.  I'll do pppol2tp
tomorrow.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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