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Subject: Re: [PATCH 1/9] virtio-blk: validate num_queues during probe
To:     Stefano Garzarella <sgarzare@redhat.com>
Cc:     mst@redhat.com, david.kaplan@amd.com, konrad.wilk@oracle.com,
        f.hetzelt@tu-berlin.de, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>
References: <20210913055353.35219-1-jasowang@redhat.com>
 <20210913055353.35219-2-jasowang@redhat.com>
 <20210913074814.wcrrisaomlhvtmo5@steredhat>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <e225518e-77c5-3fbd-ad79-a29dae564b20@redhat.com>
Date:   Tue, 14 Sep 2021 10:29:33 +0800
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在 2021/9/13 下午3:48, Stefano Garzarella 写道:
> On Mon, Sep 13, 2021 at 01:53:45PM +0800, Jason Wang wrote:
>> If an untrusted device neogitates BLK_F_MQ but advertises a zero
>> num_queues, the driver may end up trying to allocating zero size
>> buffers where ZERO_SIZE_PTR is returned which may pass the checking
>> against the NULL. This will lead unexpected results.
>>
>> Fixing this by using single queue if num_queues is zero.
>>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Stefan Hajnoczi <stefanha@redhat.com>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>> drivers/block/virtio_blk.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
>> index e574fbf5e6df..f130d12df4b9 100644
>> --- a/drivers/block/virtio_blk.c
>> +++ b/drivers/block/virtio_blk.c
>> @@ -498,7 +498,8 @@ static int init_vq(struct virtio_blk *vblk)
>>     err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
>>                    struct virtio_blk_config, num_queues,
>>                    &num_vqs);
>> -    if (err)
>> +    /* We need at least on virtqueue */
>
> s/on/one/
>
> The rest LGTM.
>
> Stefano


Will fix in next version.

Thanks


>
>> +    if (err || !num_vqs)
>>         num_vqs = 1;
>>
>>     num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs);
>> -- 
>> 2.25.1
>>
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>>
>