diff options
Diffstat (limited to 'system/xen/xsa/xsa184-qemuu-master.patch')
-rw-r--r-- | system/xen/xsa/xsa184-qemuu-master.patch | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa184-qemuu-master.patch b/system/xen/xsa/xsa184-qemuu-master.patch new file mode 100644 index 0000000000..ef96bff80c --- /dev/null +++ b/system/xen/xsa/xsa184-qemuu-master.patch @@ -0,0 +1,43 @@ +From e469db25d6b2e5c71cd15451889226641c53a5cd Mon Sep 17 00:00:00 2001 +From: P J P <ppandit@redhat.com> +Date: Mon, 25 Jul 2016 17:37:18 +0530 +Subject: [PATCH] virtio: error out if guest exceeds virtqueue size + +A broken or malicious guest can submit more requests than the virtqueue +size permits. + +The guest can submit requests without bothering to wait for completion +and is therefore not bound by virtqueue size. This requires reusing +vring descriptors in more than one request, which is incorrect but +possible. Processing a request allocates a VirtQueueElement and +therefore causes unbounded memory allocation controlled by the guest. + +Exit with an error if the guest provides more requests than the +virtqueue size permits. This bounds memory allocation and makes the +buggy guest visible to the user. + +Reported-by: Zhenhao Hong <zhenhaohong@gmail.com> +Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> +--- + hw/virtio/virtio.c | 5 +++++ + 1 file changed, 5 insertions(+) + +diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c +index d24f775..f8ac0fb 100644 +--- a/hw/virtio/virtio.c ++++ b/hw/virtio/virtio.c +@@ -483,6 +483,11 @@ int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem) + + max = vq->vring.num; + ++ if (vq->inuse >= max) { ++ error_report("Virtqueue size exceeded"); ++ exit(1); ++ } ++ + i = head = virtqueue_get_head(vq, vq->last_avail_idx++); + if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) { + vring_set_avail_event(vq, vq->last_avail_idx); +-- +2.1.4 + |