On Tue, Nov 10, 2020 at 1:16 AM Mao Wenan <wenan.mao@xxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Thanks !
