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Subject: Re: [PATCH v5] virtio-blk: Add validation for block size in config
 space
To:     Yongji Xie <xieyongji@bytedance.com>
Cc:     "Michael S. Tsirkin" <mst@redhat.com>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        virtualization <virtualization@lists.linux-foundation.org>,
        linux-block@vger.kernel.org,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <20210809101609.148-1-xieyongji@bytedance.com>
 <08366773-76b5-be73-7e32-d9ce6f6799bf@redhat.com>
 <CACycT3tPR30RU8XmWbDA=Hp-A6BBifd-q_aqrmU-9VK=OaRJRg@mail.gmail.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <46c513b4-6644-d4b0-84f4-32df34b6d7b8@redhat.com>
Date:   Tue, 10 Aug 2021 14:59:41 +0800
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在 2021/8/10 下午12:59, Yongji Xie 写道:
> On Tue, Aug 10, 2021 at 11:05 AM Jason Wang <jasowang@redhat.com> wrote:
>>
>> 在 2021/8/9 下午6:16, Xie Yongji 写道:
>>> An untrusted device might presents an invalid block size
>>> in configuration space. This tries to add validation for it
>>> in the validate callback and clear the VIRTIO_BLK_F_BLK_SIZE
>>> feature bit if the value is out of the supported range.
>>>
>>> And we also double check the value in virtblk_probe() in
>>> case that it's changed after the validation.
>>>
>>> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
>>> ---
>>>    drivers/block/virtio_blk.c | 39 +++++++++++++++++++++++++++++++++------
>>>    1 file changed, 33 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
>>> index 4b49df2dfd23..afb37aac09e8 100644
>>> --- a/drivers/block/virtio_blk.c
>>> +++ b/drivers/block/virtio_blk.c
>>> @@ -692,6 +692,28 @@ static const struct blk_mq_ops virtio_mq_ops = {
>>>    static unsigned int virtblk_queue_depth;
>>>    module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
>>>
>>> +static int virtblk_validate(struct virtio_device *vdev)
>>> +{
>>> +     u32 blk_size;
>>> +
>>> +     if (!vdev->config->get) {
>>> +             dev_err(&vdev->dev, "%s failure: config access disabled\n",
>>> +                     __func__);
>>> +             return -EINVAL;
>>> +     }
>>> +
>>> +     if (!virtio_has_feature(vdev, VIRTIO_BLK_F_BLK_SIZE))
>>> +             return 0;
>>> +
>>> +     blk_size = virtio_cread32(vdev,
>>> +                     offsetof(struct virtio_blk_config, blk_size));
>>> +
>>> +     if (blk_size < SECTOR_SIZE || blk_size > PAGE_SIZE)
>>> +             __virtio_clear_bit(vdev, VIRTIO_BLK_F_BLK_SIZE);
>>
>> I wonder if it's better to just fail here as what we did for probe().
>>
> Looks like we don't need to do that since we already clear the
> VIRTIO_BLK_F_BLK_SIZE to tell the device that we don't use the block
> size in configuration space. Just like what we did in
> virtnet_validate().
>
> Thanks,
> Yongji


Ok, so

Acked-by: Jason Wang <jasowang@redhat.com>


>