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References: <20231201143821.1091005-1-aleksander.lobakin@intel.com> <20231207115751.GG50400@kernel.org>
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From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 7 Dec 2023 13:48:52 +0100
Message-ID: <CANn89iKiiexYLXP1fW3anaZt0TJWPUBBmXdjsAV8t3CH3Ra8aw@mail.gmail.com>
Subject: Re: [PATCH iwl] idpf: fix corrupted frames and skb leaks in singleq mode
To:     Simon Horman <horms@kernel.org>
Cc:     Alexander Lobakin <aleksander.lobakin@intel.com>,
        intel-wired-lan@lists.osuosl.org,
        Michal Kubiak <michal.kubiak@intel.com>,
        Przemek Kitszel <przemyslaw.kitszel@intel.com>,
        Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Thu, Dec 7, 2023 at 12:58=E2=80=AFPM Simon Horman <horms@kernel.org> wro=
te:
>
> On Fri, Dec 01, 2023 at 03:38:21PM +0100, Alexander Lobakin wrote:
> > idpf_ring::skb serves only for keeping an incomplete frame between
> > several NAPI Rx polling cycles, as one cycle may end up before
> > processing the end of packet descriptor. The pointer is taken from
> > the ring onto the stack before entering the loop and gets written
> > there after the loop exits. When inside the loop, only the onstack
> > pointer is used.
> > For some reason, the logics is broken in the singleq mode, where the
> > pointer is taken from the ring each iteration. This means that if a
> > frame got fragmented into several descriptors, each fragment will have
> > its own skb, but only the last one will be passed up the stack
> > (containing garbage), leaving the rest leaked.
> > Just don't touch the ring skb field inside the polling loop, letting
> > the onstack skb pointer work as expected: build a new skb if it's the
> > first frame descriptor and attach a frag otherwise.
> >
> > Fixes: a5ab9ee0df0b ("idpf: add singleq start_xmit and napi poll")
> > Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
> > Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
> > Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
>
> Reviewed-by: Simon Horman <horms@kernel.org>

It seems singlequeue mode is not really used on idpf :)

Reviewed-by: Eric Dumazet <edumazet@google.com>