From: Alexey Kodanev <[email protected]>
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 <[email protected]>
Applied.
