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 <pbonz...@redhat.com>
Cc: Stefan Hajnoczi <stefa...@redhat.com>
Signed-off-by: Jason Wang <jasow...@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 */
+ 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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