When a virtqueue size is changed by the guest via
virtio_queue_set_num(), its region cache is not automatically updated.
If the size was increased, this could lead to accessing the cache out
of bounds. For example, in vring_get_used_event():
static inline uint16_t vring_get_used_event(VirtQueue *vq)
{
return vring_avail_ring(vq, vq->vring.num);
}
static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
hwaddr pa = offsetof(VRingAvail, ring[i]);
if (!caches) {
return 0;
}
return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
}
vq->vring.num will be greater than caches->avail.len, which will
trigger a failed assertion down the call path of
virtio_lduw_phys_cached().
Fix this by calling virtio_queue_update_rings() after
virtio_queue_set_num() if we are not already calling
virtio_queue_set_rings().
Signed-off-by: Carlos López <clopez@suse.de>
---
hw/s390x/virtio-ccw.c | 1 +
hw/virtio/virtio-mmio.c | 5 ++---
hw/virtio/virtio-pci.c | 1 +
3 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index e33e5207ab..89891ac58a 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -237,6 +237,7 @@ static int virtio_ccw_set_vqs(SubchDev *sch, VqInfoBlock
*info,
return -EINVAL;
}
virtio_queue_set_num(vdev, index, num);
+ virtio_queue_update_rings(vdev, index);
} else if (virtio_queue_get_num(vdev, index) > num) {
/* Fail if we don't have a big enough queue. */
return -EINVAL;