在 2021/8/10 下午12:59, Yongji Xie 写道:

On Tue, Aug 10, 2021 at 11:05 AM Jason Wang [off-list ref] wrote:

quoted

在 2021/8/9 下午6:16, Xie Yongji 写道:

quoted

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 <redacted>
---
   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>