From: David Miller <davem@davemloft.net>
To: alexey.kodanev@oracle.com
Cc: netdev@vger.kernel.org, fw@strlen.de, edumazet@google.com
Subject: Re: [PATCH v2 1/2] tcp: setup timestamp offset when write_seq already set
Date: Wed, 22 Feb 2017 16:33:37 -0500 (EST) [thread overview]
Message-ID: <20170222.163337.1789197655018339564.davem@davemloft.net> (raw)
In-Reply-To: <1487759036-2800-1-git-send-email-alexey.kodanev@oracle.com>
From: Alexey Kodanev <alexey.kodanev@oracle.com>
Date: Wed, 22 Feb 2017 13:23:55 +0300
> Found that when randomized tcp offsets are enabled (by default)
> TCP client can still start new connections without them. Later,
> if server does active close and re-uses sockets in TIME-WAIT
> state, new SYN from client can be rejected on PAWS check inside
> tcp_timewait_state_process(), because either tw_ts_recent or
> rcv_tsval doesn't really have an offset set.
>
> Here is how to reproduce it with LTP netstress tool:
> netstress -R 1 &
> netstress -H 127.0.0.1 -lr 1000000 -a1
>
> [...]
> < S seq 1956977072 win 43690 TS val 295618 ecr 459956970
> > . ack 1956911535 win 342 TS val 459967184 ecr 1547117608
> < R seq 1956911535 win 0 length 0
> +1. < S seq 1956977072 win 43690 TS val 296640 ecr 459956970
> > S. seq 657450664 ack 1956977073 win 43690 TS val 459968205 ecr 296640
>
> Fixes: 95a22caee396 ("tcp: randomize tcp timestamp offsets for each connection")
> Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Applied.
prev parent reply other threads:[~2017-02-22 21:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-22 10:23 [PATCH v2 1/2] tcp: setup timestamp offset when write_seq already set Alexey Kodanev
2017-02-22 10:23 ` [PATCH v2 2/2] tcp: account for ts offset only if tsecr not zero Alexey Kodanev
2017-02-22 13:32 ` Eric Dumazet
2017-02-22 21:34 ` David Miller
2017-02-22 13:17 ` [PATCH v2 1/2] tcp: setup timestamp offset when write_seq already set Eric Dumazet
2017-02-22 14:31 ` Alexey Kodanev
2017-02-22 21:33 ` David Miller [this message]
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