From: Brian Foley <brian.foley@xxxxxxx>
If a virtio device reports a QueueNumMax of 0, vring_new_virtqueue()
doesn't check this, and thanks to an unsigned (i < num - 1) loop
guard, scribbles over memory when initialising the free list.
Avoid by not trying to create zero-descriptor queues, as there's no
way to do any I/O with one.
Signed-off-by: Brian Foley <brian.foley@xxxxxxx>
Signed-off-by: Pawel Moll <pawel.moll@xxxxxxx>
---
drivers/virtio/virtio_mmio.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 58e2d78..6979c1b 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -332,6 +332,16 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
* and two rings (which makes it "alignment_size * 2")
*/
info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
+
+ /* If the device reports a 0 entry queue, we won't be able to
+ * use it to perform I/O, and vring_new_virtqueue() can't create
+ * empty queues anyway, so don't bother to set up the device.
+ */
+ if (info->num == 0) {
+ err = -ENOENT;
+ goto error_alloc_pages;
+ }
+
while (1) {
size = PAGE_ALIGN(vring_size(info->num,
VIRTIO_MMIO_VRING_ALIGN));
--
1.7.9.5
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