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Date:   Mon, 14 Feb 2022 21:21:36 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Haiyue Wang <haiyue.wang@intel.com>
Cc:     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>,
        Willem de Bruijn <willemb@google.com>,
        Bailey Forrest <bcf@google.com>, Tao Liu <xliutaox@google.com>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        John Fraker <jfraker@google.com>,
        Yangchun Fu <yangchun@google.com>,
        linux-kernel@vger.kernel.org (open list)
Subject: Re: [PATCH v1] gve: fix zero size queue page list allocation
Message-ID: <20220214212136.71e5b4c6@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
In-Reply-To: <20220214024134.223939-1-haiyue.wang@intel.com>
References: <20220214024134.223939-1-haiyue.wang@intel.com>
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On Mon, 14 Feb 2022 10:41:29 +0800 Haiyue Wang wrote:
> According to the two functions 'gve_num_tx/rx_qpls', only the queue with
> GVE_GQI_QPL_FORMAT format has queue page list.
> 
> 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.
> 
> Use the queue page list number to detect no QPLs, it can avoid zero size
> queue page list memory allocation.

There's no bug here, strictly speaking, the driver will function
correctly? In that case please repost without the Fixes tag and
with [PATCH net-next] in the subject.

> Fixes: a5886ef4f4bf ("gve: Introduce per netdev `enum gve_queue_format`")
> Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>