From 758ead31c7e17bf17a9ef2e0ca1c3e86ab296b43 Mon Sep 17 00:00:00 2001 From: Prasad J Pandit Date: Wed, 29 Nov 2017 23:14:27 +0530 Subject: [PATCH] virtio: check VirtQueue Vring object is set A guest could attempt to use an uninitialised VirtQueue object or unset Vring.align leading to a arithmetic exception. Add check to avoid it. Upstream-Status: Backport CVE: CVE-2017-17381 Reported-by: Zhangboxian Signed-off-by: Prasad J Pandit Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Stefan Hajnoczi Reviewed-by: Cornelia Huck Signed-off-by: Catalin Enache --- 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 703e672..ad564b0 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 (!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) { + 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) -- 2.10.2