netdev - Re: [PATCH net] inet: clear num_timeout reqsk

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Date:   Wed, 19 Jun 2019 17:48:17 -0400 (EDT)
From:   David Miller <davem@...hat.com>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com, ycheng@...gle.com,
        ncardwell@...gle.com, soheil@...gle.com, syzkaller@...glegroups.com
Subject: Re: [PATCH net] inet: clear num_timeout reqsk_alloc()

From: Eric Dumazet <edumazet@...gle.com>
Date: Wed, 19 Jun 2019 09:38:38 -0700

> KMSAN caught uninit-value in tcp_create_openreq_child() [1]
> This is caused by a recent change, combined by the fact
> that TCP cleared num_timeout, num_retrans and sk fields only
> when a request socket was about to be queued.
> 
> Under syncookie mode, a temporary request socket is used,
> and req->num_timeout could contain garbage.
> 
> Lets clear these three fields sooner, there is really no
> point trying to defer this and risk other bugs.
> 
> [1]
> 
> BUG: KMSAN: uninit-value in tcp_create_openreq_child+0x157f/0x1cc0 net/ipv4/tcp_minisocks.c:526
 ...
> Fixes: 336c39a03151 ("tcp: undo init congestion window on false SYNACK timeout")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Yuchung Cheng <ycheng@...gle.com>
> Cc: Neal Cardwell <ncardwell@...gle.com>
> Cc: Soheil Hassas Yeganeh <soheil@...gle.com>
> Reported-by: syzbot <syzkaller@...glegroups.com>

Applied, thanks Eric.