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Date:   Tue, 10 Nov 2020 17:45:01 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Eric Dumazet <edumazet@google.com>
Cc:     Mao Wenan <wenan.mao@linux.alibaba.com>,
        David Miller <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        kernel-janitors@vger.kernel.org
Subject: Re: [PATCH net v5] net: Update window_clamp if SOCK_RCVBUF is set
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On Tue, 10 Nov 2020 08:32:52 +0100 Eric Dumazet wrote:
> On Tue, Nov 10, 2020 at 1:16 AM Mao Wenan <wenan.mao@linux.alibaba.com> wrote:
> > When net.ipv4.tcp_syncookies=1 and syn flood is happened,
> > cookie_v4_check or cookie_v6_check tries to redo what
> > tcp_v4_send_synack or tcp_v6_send_synack did,
> > rsk_window_clamp will be changed if SOCK_RCVBUF is set,
> > which will make rcv_wscale is different, the client
> > still operates with initial window scale and can overshot
> > granted window, the client use the initial scale but local
> > server use new scale to advertise window value, and session
> > work abnormally.
> >
> > Fixes: e88c64f0a425 ("tcp: allow effective reduction of TCP's rcv-buffer via setsockopt")
> > Signed-off-by: Mao Wenan <wenan.mao@linux.alibaba.com>  
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied, thanks!