File 0257-virtio-check-VirtQueue-Vring-object.patch of Package qemu-linux-user.29142

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File 0257-virtio-check-VirtQueue-Vring-object.patch of Package qemu-linux-user.29142

From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Wed, 29 Nov 2017 23:14:27 +0530
Subject: 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.

Reported-by: Zhangboxian <zhangboxian@huawei.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
(cherry picked from commit 758ead31c7e17bf17a9ef2e0ca1c3e86ab296b43)
[LY: bsc#1071228 CVE-2017-17381]
Signed-off-by: Liang Yan <lyan@suse.com>
---
 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 12c8712734bef86b6da3df9e45b7..a17d7dfc2034a49cca082883dd63 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -108,7 +108,7 @@ 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;
     }
@@ -1021,6 +1021,9 @@ 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);
 }
@@ -1033,6 +1036,9 @@ 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;
@@ -1102,8 +1108,10 @@ 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 void virtio_queue_notify_aio_vq(VirtQueue *vq)

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File 0257-virtio-check-VirtQueue-Vring-object.patch of Package qemu-linux-user.29142

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