Re: [PATCH] tcp: fix syncookie regression

From: Eric Dumazet <redacted>
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 <redacted>
Bisected-by: Simon Kirby [off-list ref]
Signed-off-by: Eric Dumazet <redacted>
Tested-by: Eric Dumazet <redacted>

Applied and queued up for -stable, thanks.