netdev - Re: [PATCH net 1/2] tcp: clear icsk_backoff in tcp_write_queue

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Date:   Fri, 15 Feb 2019 21:21:56 -0500
From:   Neal Cardwell <ncardwell@...gle.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        soukjin bae <soukjin.bae@...sung.com>
Subject: Re: [PATCH net 1/2] tcp: clear icsk_backoff in tcp_write_queue_purge()

On Fri, Feb 15, 2019 at 4:36 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> soukjin bae reported a crash in tcp_v4_err() handling
> ICMP_DEST_UNREACH after tcp_write_queue_head(sk)
> returned a NULL pointer.
>
> Current logic should have prevented this :
>
>   if (seq != tp->snd_una  || !icsk->icsk_retransmits ||
>       !icsk->icsk_backoff || fastopen)
>       break;
>
> Problem is the write queue might have been purged
> and icsk_backoff has not been cleared.
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: soukjin bae <soukjin.bae@...sung.com>
> ---
>  net/ipv4/tcp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Neal Cardwell <ncardwell@...gle.com>

Thanks!

neal