A queue size of 0 is used to indicate a nonexistent queue, so
don't allow the guest to flip a queue between zero-size and
non-zero-size. Don't permit setting of negative queue sizes
either.
Signed-off-by: Peter Maydell <peter.maydell@xxxxxxxxxx>
---
hw/virtio/virtio.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 09f62c6..60653f7 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -673,10 +673,16 @@ hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n)
void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
{
- if (num <= VIRTQUEUE_MAX_SIZE) {
- vdev->vq[n].vring.num = num;
- virtqueue_init(&vdev->vq[n]);
+ /* Don't allow guest to flip queue between existent and
+ * nonexistent states, or to set it to an invalid size.
+ */
+ if (!!num != !!vdev->vq[n].vring.num ||
+ num > VIRTQUEUE_MAX_SIZE ||
+ num < 0) {
+ return;
}
+ vdev->vq[n].vring.num = num;
+ virtqueue_init(&vdev->vq[n]);
}
int virtio_queue_get_num(VirtIODevice *vdev, int n)
--
1.7.9.5
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