From: Michael S. Tsirkin <mst@redhat.com>
Date: Wed, 4 Mar 2015 16:14:08 +0000 (+0000)
Subject: virtio: out-of-bounds buffer write on invalid state load
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=2ee75346e69ec5ab5f36c90e2e2aa8e8bfd3c7dc;p=qemu-xen.git

virtio: out-of-bounds buffer write on invalid state load

CVE-2013-4151 QEMU 1.0 out-of-bounds buffer write in
virtio_load@hw/virtio/virtio.c

So we have this code since way back when:

    num = qemu_get_be32(f);

    for (i = 0; i < num; i++) {
        vdev->vq[i].vring.num = qemu_get_be32(f);

array of vqs has size VIRTIO_PCI_QUEUE_MAX, so
on invalid input this will write beyond end of buffer.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---

diff --git a/hw/virtio.c b/hw/virtio.c
index f40a8c5571..d920419b7e 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -812,7 +812,8 @@ int virtio_set_features(VirtIODevice *vdev, uint32_t val)
 
 int virtio_load(VirtIODevice *vdev, QEMUFile *f)
 {
-    int num, i, ret;
+    int i, ret;
+    uint32_t num;
     uint32_t features;
     uint32_t supported_features;
 
@@ -838,6 +839,11 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f)
 
     num = qemu_get_be32(f);
 
+    if (num > VIRTIO_PCI_QUEUE_MAX) {
+        error_report("Invalid number of PCI queues: 0x%x", num);
+        return -1;
+    }
+
     for (i = 0; i < num; i++) {
         vdev->vq[i].vring.num = qemu_get_be32(f);
         vdev->vq[i].pa = qemu_get_be64(f);