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Date:   Thu, 7 Dec 2023 11:57:51 +0000
From:   Simon Horman <horms@kernel.org>
To:     Alexander Lobakin <aleksander.lobakin@intel.com>
Cc:     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>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH iwl] idpf: fix corrupted frames and skb leaks in singleq
 mode
Message-ID: <20231207115751.GG50400@kernel.org>
References: <20231201143821.1091005-1-aleksander.lobakin@intel.com>
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In-Reply-To: <20231201143821.1091005-1-aleksander.lobakin@intel.com>
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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>