netdev - Re: [PATCH] packet: fix potential use after free

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Date:	Fri, 11 Apr 2014 15:59:22 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	dborkman@...hat.com, netdev@...r.kernel.org, xii@...gle.com
Subject: Re: [PATCH] packet: fix potential use after free

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Thu, 10 Apr 2014 08:06:58 -0700

> On Thu, 2014-04-10 at 10:19 +0200, Daniel Borkmann wrote:
>> On 04/10/2014 03:22 AM, Eric Dumazet wrote:
>> > From: Eric Dumazet <edumazet@...gle.com>
>> >
>> > As soon skb is queued into sk_receive_queue, it can be consumed,
>> > so its racy to access skb->len.
>> >
>> > Given that sk_data_ready() / sock_def_readable() don't really care, just
>> > use 0 instead of skb->len
>> >
>> > Signed-off-by: Eric Dumazet <edumazet@...gle.com>
>> > Cc: Xi Wang <xii@...gle.com>
>> 
>> Acked-by: Daniel Borkmann <dborkman@...hat.com>
>> 
>> Seems to be there since pre 2005 ...
> 
> Yeah, and many other places have the same error, a full audit is
> probably needed.

Not only sock_def_readable(), but all implementations of this callback absolutely
do not care about the length argument.

I'm working on a patch to kill the argument completely.
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