Re: [PATCH v2 net] tcp: md5: incorrect tcp_header_len for incoming connections

From: Francesco Ruggeri <fruggeri@arista.com>
To: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>, Jakub Kicinski <kuba@kernel.org>,
	David Ahern <dsahern@kernel.org>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	David Miller <davem@davemloft.net>,
	LKML <linux-kernel@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH v2 net] tcp: md5: incorrect tcp_header_len for incoming connections
Date: Mon, 25 Apr 2022 10:55:52 -0700	[thread overview]
Message-ID: <CA+HUmGj_rM43PTpz3nsn8=8r7vR1jcKB2_CMJBHejM7T-3S_xw@mail.gmail.com> (raw)
In-Reply-To: <CANn89iKM-f=VLfwb9wq8+_bmaLjP_Xg5CanqJWhans2DXE=v5w@mail.gmail.com>

On Sun, Apr 24, 2022 at 12:37 PM Eric Dumazet <edumazet@google.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