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From:   Jason Wang <jasowang@redhat.com>
Date:   Fri, 14 Jul 2023 11:58:46 +0800
Message-ID: <CACGkMEvq8h_yYhxBWD4oPBBwE8xzDMt7VqbW4wz+oqjfYbiQfQ@mail.gmail.com>
Subject: Re: [PATCH v2 net] gso: fix dodgy bit handling for GSO_UDP_L4
To:     Yan Zhai <yan@cloudflare.com>
Cc:     "open list:NETWORKING [TCP]" <netdev@vger.kernel.org>,
        kernel-team@cloudflare.com, Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        David Ahern <dsahern@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
        Xin Long <lucien.xin@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Andrew Melnychenko <andrew@daynix.com>,
        Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:SCTP PROTOCOL" <linux-sctp@vger.kernel.org>
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On Fri, Jul 14, 2023 at 1:28=E2=80=AFAM Yan Zhai <yan@cloudflare.com> wrote=
:
>
> Commit 1fd54773c267 ("udp: allow header check for dodgy GSO_UDP_L4
> packets.") checks DODGY bit for UDP, but for packets that can be fed
> directly to the device after gso_segs reset, it actually falls through
> to fragmentation:
>
> https://lore.kernel.org/all/CAJPywTKDdjtwkLVUW6LRA2FU912qcDmQOQGt2WaDo28K=
zYDg+A@mail.gmail.com/
>
> This change restores the expected behavior of GSO_UDP_L4 packets.
>
> Fixes: 1fd54773c267 ("udp: allow header check for dodgy GSO_UDP_L4 packet=
s.")
> Suggested-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> Signed-off-by: Yan Zhai <yan@cloudflare.com>
>
> ---
> v2: dropped modifications to tcp/sctp on DODGY bit removal after
> validating gso_segs. Also moved the UDP header check into
> __udp_gso_segment (per Willem's suggestion).
>

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks