linux-kernel - Re: [PATCH v2 net] tcp: md5: incorrect tcp_header

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Message-ID: <CA+HUmGj_rM43PTpz3nsn8=8r7vR1jcKB2_CMJBHejM7T-3S_xw@mail.gmail.com>
Date:   Mon, 25 Apr 2022 10:55:52 -0700
From:   Francesco Ruggeri <fruggeri@...sta.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Paolo Abeni <pabeni@...hat.com>, Jakub Kicinski <kuba@...nel.org>,
        David Ahern <dsahern@...nel.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Miller <davem@...emloft.net>,
        LKML <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH v2 net] tcp: md5: incorrect tcp_header_len for incoming connections

On Sun, Apr 24, 2022 at 12:37 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> Wait a minute.
>
> Are you sure treq->af_specific is initialized at this point ?
>
> I should have tested this one liner patch really :/
>
> I think that for syncookies, treq->af_specific is not initialized,
> because we do not go through
> tcp_conn_request() helper, but instead use cookie_tcp_reqsk_alloc()
>
> Before your patch treq->af_specific was only used during SYNACK
> generation, which does not happen in syncookie more while receiving
> the third packet.
>
> I will test something like this patch. We could move the init after
> cookie_tcp_reqsk_alloc() has been called, but I prefer using the same
> construct than tcp_conn_request()
>

Thanks for fixing this Eric. I had not considered syncookies.

Francesco