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References: <20220214024134.223939-1-haiyue.wang@intel.com> <20220215051751.260866-1-haiyue.wang@intel.com>
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From:   Bailey Forrest <bcf@google.com>
Date:   Tue, 15 Feb 2022 10:04:42 -0800
Message-ID: <CANH7hM5tYYU7GyYLboEVdin6xivV3LmbPxMxEa3sxb_YEBfH8w@mail.gmail.com>
Subject: Re: [PATCH net-next v2] gve: enhance no queue page list detection
To:     Haiyue Wang <haiyue.wang@intel.com>
Cc:     Networking <netdev@vger.kernel.org>,
        Jeroen de Borst <jeroendb@google.com>,
        Catherine Sullivan <csully@google.com>,
        David Awogbemila <awogbemila@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Willem de Bruijn <willemb@google.com>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        Tao Liu <xliutaox@google.com>,
        John Fraker <jfraker@google.com>,
        Yangchun Fu <yangchun@google.com>,
        open list <linux-kernel@vger.kernel.org>
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On Mon, Feb 14, 2022 at 9:52 PM Haiyue Wang <haiyue.wang@intel.com> wrote:
>
> The commit
> a5886ef4f4bf ("gve: Introduce per netdev `enum gve_queue_format`")
> introduces three queue format type, only GVE_GQI_QPL_FORMAT queue has
> page list. So it should use the queue page list number to detect the
> zero size queue page list. Correct the design logic.
>
> Using the 'queue_format == GVE_GQI_RDA_FORMAT' may lead to request zero
> sized memory allocation, like if the queue format is GVE_DQO_RDA_FORMAT.
>
> The kernel memory subsystem will return ZERO_SIZE_PTR, which is not NULL
> address, so the driver can run successfully. Also the code still checks
> the queue page list number firstly, then accesses the allocated memory,
> so zero number queue page list allocation will not lead to access fault.
>
> Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>

Reviewed-by: Bailey Forrest <bcf@google.com>