On Thu, Jun 17, 2021 at 01:10:04PM +0800, Xie Yongji wrote:
quoted hunk
This ensures that we will not use an invalid block size
in config space (might come from an untrusted device).
Signed-off-by: Xie Yongji <redacted>
---
drivers/block/virtio_blk.c | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index b9fa3ef5b57c..bbdae989f1ea 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -696,6 +696,28 @@ 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);
+
+ return 0;
+}
I saw Michael asked for .validate() in v2. I would prefer to keep
everything in virtblk_probe() instead of adding .validate() because:
- There is a race condition that an untrusted device can exploit since
virtblk_probe() fetches the value again.
- It's more complex now that .validate() takes a first shot at blk_size
and then virtblk_probe() deals with it again later on.