netdev - Re: [PATCH] ipv6: udp packets following an UFO enqueued packet need also be handled by UFO

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Message-ID: <20130923004343.GD22033@order.stressinduktion.org>
Date:	Mon, 23 Sep 2013 02:43:43 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	netdev@...r.kernel.org, yoshfuji@...ux-ipv6.org,
	davem@...emloft.net, dvyukov@...gle.com
Cc:	pjt@...gle.com, andreyknvl@...gle.com, kcc@...gle.com,
	therbert@...gle.com
Subject: Re: [PATCH] ipv6: udp packets following an UFO enqueued packet need also be handled by UFO

On Sat, Sep 21, 2013 at 06:27:00AM +0200, Hannes Frederic Sowa wrote:
> In the following scenario the socket is corked:
> If the first UDP packet is larger then the mtu we try to append it to the
> write queue via ip6_ufo_append_data. A following packet, which is smaller
> than the mtu would be appended to the already queued up gso-skb via
> plain ip6_append_data. This causes random memory corruptions.
> 
> In ip6_ufo_append_data we also have to be careful to not queue up the
> same skb multiple times. So setup the gso frame only when no first skb
> is available.
> 
> This also fixes a shortcoming where we add the current packet's length to
> cork->length but return early because of a packet > mtu with dontfrag set
> (instead of sutracting it again).
> 
> Found with trinity.
> 
> Cc: YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
> Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>

Further analysis showed it is very probable that this fixes the bug Dmitry
reported. So I want to give proper credits:

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>

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