On Sat, 25 Nov 2017 00:04:45 +0530
P J P <ppan...@redhat.com> wrote:
> From: Prasad J Pandit <p...@fedoraproject.org>
>
> An user could attempt to use an uninitialised VirtQueue object
s/An user/A guest/ ?
> or unset Vring.align leading to a arithmetic exception. Add check
> to avoid it.
>
> Reported-by: Zhangboxian <zhangbox...@huawei.com>
> Signed-off-by: Prasad J Pandit <p...@fedoraproject.org>
> ---
> hw/virtio/virtio.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 5884ce3480..c01eac87a5 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -182,7 +182,7 @@ void virtio_queue_update_rings(VirtIODevice *vdev, int n)
> {
> VRing *vring = &vdev->vq[n].vring;
>
> - if (!vring->desc) {
> + if (!vdev->vq[n].vring.num || !vring->desc || !vring->align) {
> /* not yet setup -> nothing to do */
> return;
> }
> @@ -1414,6 +1414,9 @@ void virtio_config_modern_writel(VirtIODevice *vdev,
>
> void virtio_queue_set_addr(VirtIODevice *vdev, int n, hwaddr addr)
> {
> + if (!vdev->vq[n].vring.num) {
> + return;
> + }
> vdev->vq[n].vring.desc = addr;
> virtio_queue_update_rings(vdev, n);
> }
> @@ -1426,6 +1429,9 @@ hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n)
> void virtio_queue_set_rings(VirtIODevice *vdev, int n, hwaddr desc,
> hwaddr avail, hwaddr used)
> {
> + if (!vdev->vq[n].vring.num || !desc || !vdev->vq[n].vring.align) {
Checking for !desc is wrong (why shouldn't a driver be able to unset a
descriptor table?)
The check for align is not really needed, as virtio-1 disallows setting
align anyway.
> + return;
> + }
> vdev->vq[n].vring.desc = desc;
> vdev->vq[n].vring.avail = avail;
> vdev->vq[n].vring.used = used;
> @@ -1494,8 +1500,10 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n,
> int align)
> */
> assert(k->has_variable_vring_alignment);
>
> - vdev->vq[n].vring.align = align;
> - virtio_queue_update_rings(vdev, n);
> + if (align) {
> + vdev->vq[n].vring.align = align;
> + virtio_queue_update_rings(vdev, n);
> + }
> }
>
> static bool virtio_queue_notify_aio_vq(VirtQueue *vq)
