From f0d634ea1964ccce317818c44fe299e71007e64d Mon Sep 17 00:00:00 2001 From: Carlos López Date: Fri, 17 Mar 2023 01:27:51 +0100 Subject: virtio: refresh vring region cache after updating a virtqueue size MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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_init_region_cache() after virtio_queue_set_num() if we are not already calling virtio_queue_set_rings(). In the legacy path this is already done by virtio_queue_update_rings(). Signed-off-by: Carlos López Message-Id: <20230317002749.27379-1-clopez@suse.de> Reviewed-by: Cornelia Huck Acked-by: Halil Pasic Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/virtio-pci.c | 1 + 1 file changed, 1 insertion(+) (limited to 'hw/virtio/virtio-pci.c') diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index 247325c193..02fb84a8fa 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -1554,6 +1554,7 @@ static void virtio_pci_common_write(void *opaque, hwaddr addr, proxy->vqs[vdev->queue_sel].num = val; virtio_queue_set_num(vdev, vdev->queue_sel, proxy->vqs[vdev->queue_sel].num); + virtio_init_region_cache(vdev, vdev->queue_sel); break; case VIRTIO_PCI_COMMON_Q_MSIX: vector = virtio_queue_vector(vdev, vdev->queue_sel); -- cgit 1.4.1