netdev - Re: [PATCH 1/4] net: check for reference outside of skb

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Message-Id: <20100802.155937.58423604.davem@davemloft.net>
Date:	Mon, 02 Aug 2010 15:59:37 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	shemminger@...tta.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH 1/4] net: check for reference outside of skb

From: Stephen Hemminger <shemminger@...tta.com>
Date: Mon, 02 Aug 2010 15:00:31 -0700

> It is legitimate for callers of skb_header_pointer to pass a negative
> offset, but the resulting pointer should not go outside the valid
> range of data in the skb.
> 
> Signed-off-by: Stephen Hemminger <shemminger@...tta.com>

Stephen, it seems to me that most existing (if not all) callers of
skb_header_pointer() already can prove that their offsets are
legitimate, negative or not.  They usually do this via pskb_may_pull()
or similar.

Therefore it makes no sense to me that we punish all existing code paths
with a duplicate test just to have this check available for use in u32.

Just put the range test in u32.

Thanks.

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