linux-kernel - Re: [PATCH] gro: check returned skb of napi_frags

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Message-ID: <CANn89iKxGVDQba1UCbpYKhNo=rZXuN2j=610DbJx0z=kWa7N3w@mail.gmail.com>
Date:   Thu, 6 Jul 2023 15:52:50 +0200
From:   Eric Dumazet <edumazet@...gle.com>
To:     Kaiyu Zhang <squirrel.prog@...il.com>
Cc:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gro: check returned skb of napi_frags_skb() against NULL

On Thu, Jul 6, 2023 at 3:08 PM Kaiyu Zhang <squirrel.prog@...il.com> wrote:
>
> Some rogue network adapter and their driver pass bad skbs to GRO.
> napi_frags_skb() detects this, drops these bad skbs, and return NULL
> to napi_gro_frags(), which does not check returned skb against NULL
> and access it. This results in a kernel crash.
>
> A better approach to address these bad skbs would be to issue some
> warnings and drop them, which napi_frags_skb() already does, and
> move on without crashing the kernel.
>

Certainly not.

We are not going to try to be nice to buggy drivers.

Please fix the "rogue network adapter" instead.