From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH] ipv6: check if dereference of ipv6 header is safe
Date: Fri, 18 Jan 2013 11:12:26 -0800
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To: Hannes Frederic Sowa <hannes@stressinduktion.org>
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On Fri, 2013-01-18 at 04:08 +0100, Hannes Frederic Sowa wrote:

> Please correct me if I am wrong:
> 
> The callstack as captured in ipip6_rcv:
>     ipip6_rcv+0xcd/0x680 [sit]
>     tunnel64_rcv+0x4a/0x174 [tunnel4]
>     ip_local_deliver+0x152/0x470
>     ? ip_local_deliver+0x75/0x470
>     ip_rcv+0x36d/0x650
> 
> ip_rcv does first check if the ipv4 header is complete (inclusive options) and
> passes control to ip_local_deliver which calls __skb_pull(skb,
> ip_hdrlen(skb)). So ->data is forwarded behind the ipv4 header. The next
> pskb_may_pull check would check if the necessary amount of data behind the
> ipv4 header is available hence I assume the check in tunnel64_rcv is enough:

Oh, yes, thats fine.