netdev - Re: [Patch net v2] mlx5: fixup checksum for short ethernet frame padding

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CANn89iLkNHpCmpAcWa0TiY3A+5vRLeP=oWrQVUEF=yXifnT5CA@mail.gmail.com>
Date:   Wed, 28 Nov 2018 19:49:49 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: Re: [Patch net v2] mlx5: fixup checksum for short ethernet frame padding

On Wed, Nov 28, 2018 at 7:40 PM Cong Wang <xiyou.wangcong@...il.com> wrote:
>
> On Wed, Nov 28, 2018 at 4:07 PM Eric Dumazet <edumazet@...gle.com> wrote:
> >
> > A NIC is supposed to deliver frames, even the ones that 'seem' bad.
>
> A quick test shows this is not the case for mlx5.
>
> With the trafgen script you gave to me, with tot_len==40, the dest host
> could receive all the packets. Changing tot_len to 80, tcpdump could no
> longer see any packet. (Both sender and receiver are mlx5.)
>
> So, packets with tot_len > skb->len are clearly dropped before tcpdump
> could see it, that is likely by mlx5 hardware.

Or a router, or a switch.

Are your two hosts connected back to back ?