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Date: Thu, 03 Aug 2006 10:11:11 -0700
From: Sam Leffler <sam@errno.com>
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To: Yar Tikhiy <yar@FreeBSD.org>
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Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/net if_vlan.c
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Yar Tikhiy wrote:
> yar         2006-08-03 09:59:09 UTC
> 
>   FreeBSD src repository
> 
>   Modified files:
>     sys/net              if_vlan.c 
>   Log:
>   Should vlan_input() ever be called with ifp pointing to a non-Ethernet
>   interface, do not just assign -1 to tag because it breaks the logic of
>   the code to follow.  The better way is to handle this case as an unsupported
>   protocol and return unless INVARIANTS is in effect and we can panic.
>   Panic is good there because the scenario can happen only because of a
>   coding error elsewhere.
>   
>   We also should show the interface name in the panic message for easier
>   debugging of the problem, should it ever emerge.

Introducing a panic in a place where you can trivially recover is bad
regardless of why you got there.  Many people run production systems
with INVARIANTS turned on.  Is it now possible to send a "packet of
death" by exploiting this code path?

	Sam