netdev - Re: [PATCH] tcp: fix syncookie regression

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Date:	Sun, 11 Mar 2012 15:54:33 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	sim@...nation.com, netdev@...r.kernel.org
Subject: Re: [PATCH] tcp: fix syncookie regression

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Sat, 10 Mar 2012 11:20:21 -0800

> commit ea4fc0d619 (ipv4: Don't use rt->rt_{src,dst} in ip_queue_xmit())
> added a serious regression on synflood handling.
> 
> Simon Kirby discovered a successful connection was delayed by 20 seconds
> before being responsive.
> 
> In my tests, I discovered that xmit frames were lost, and needed ~4
> retransmits and a socket dst rebuild before being really sent.
> 
> In case of syncookie initiated connection, we use a different path to
> initialize the socket dst, and inet->cork.fl.u.ip4 is left cleared.
> 
> As ip_queue_xmit() now depends on inet flow being setup, fix this by
> copying the temp flowi4 we use in cookie_v4_check().
> 
> Reported-by: Simon Kirby <sim@...nation.com>
> Bisected-by: Simon Kirby <sim@...nation.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
> Tested-by: Eric Dumazet <eric.dumazet@...il.com>

Applied and queued up for -stable, thanks.
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