[Qemu-devel] [PATCH v4 16/30] virtio: avoid buffer overrun on incoming migration

[Michael S. Tsirkin]

From: Michael Roth <address@hidden>

CVE-2013-6399

vdev->queue_sel is read from the wire, and later used in the
emulation code as an index into vdev->vq[]. If the value of
vdev->queue_sel exceeds the length of vdev->vq[], currently
allocated to be VIRTIO_PCI_QUEUE_MAX elements, subsequent PIO
operations such as VIRTIO_PCI_QUEUE_PFN can be used to overrun
the buffer with arbitrary data originating from the source.

Fix this by failing migration if the value from the wire exceeds
VIRTIO_PCI_QUEUE_MAX.

Signed-off-by: Michael Roth <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>
---
 hw/virtio/virtio.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 9008430..bcbfbb2 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -907,6 +907,9 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f)
     qemu_get_8s(f, &vdev->status);
     qemu_get_8s(f, &vdev->isr);
     qemu_get_be16s(f, &vdev->queue_sel);
+    if (vdev->queue_sel >= VIRTIO_PCI_QUEUE_MAX) {
+        return -1;
+    }
     qemu_get_be32s(f, &features);
 
     if (virtio_set_features(vdev, features) < 0) {
-- 
MST