From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: denys@visp.net.lb, netdev@vger.kernel.org
Subject: Re: 2.6.38.2, kernel panic, probably related to framentation handling
Date: Wed, 04 May 2011 14:05:33 -0700 (PDT) [thread overview]
Message-ID: <20110504.140533.35050081.davem@davemloft.net> (raw)
In-Reply-To: <1304539346.32152.81.camel@edumazet-laptop>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 04 May 2011 22:02:26 +0200
> [PATCH] net: ip_expire() must revalidate route
>
> Commit 4a94445c9a5c (net: Use ip_route_input_noref() in input path)
> added a bug in IP defragmentation handling, in case timeout is fired.
>
> When a frame is defragmented, we use last skb dst field when building
> final skb. Its dst is valid, since we are in rcu read section.
>
> But if a timeout occurs, we take first queued fragment to build one ICMP
> TIME EXCEEDED message. Problem is all queued skb have weak dst pointers,
> since we escaped RCU critical section after their queueing. icmp_send()
> might dereference a now freed (and possibly reused) part of memory.
>
> Calling skb_dst_drop() and ip_route_input_noref() to revalidate route is
> the only possible choice.
>
> Reported-by: Denys Fedoryshchenko <denys@visp.net.lb>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> ---
Applied to net-2.6 and queued up for -stable, thanks Eric!
prev parent reply other threads:[~2011-05-04 21:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-04 11:36 2.6.38.2, kernel panic, probably related to framentation handling Denys Fedoryshchenko
2011-05-04 17:03 ` Eric Dumazet
2011-05-04 18:09 ` Denys Fedoryshchenko
2011-05-04 18:11 ` Eric Dumazet
2011-05-04 20:02 ` Eric Dumazet
2011-05-04 21:05 ` David Miller [this message]
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