From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Wed, 27 Jul 2016 15:37:56 +0000 (+0530)
Subject: virtio: check vring descriptor buffer length
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1e7aed70144b4673fc26e73062064b6724795e5f;p=qemu.git

virtio: check vring descriptor buffer length

virtio back end uses set of buffers to facilitate I/O operations.
An infinite loop unfolds in virtqueue_pop() if a buffer was
of zero size. Add check to avoid it.

Reported-by: Li Qiang <liqiang6-s@360.cn>
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>
---

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 752b2715d0..b4d05110d2 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -458,6 +458,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
     unsigned num_sg = *p_num_sg;
     assert(num_sg <= max_num_sg);
 
+    if (!sz) {
+        error_report("virtio: zero sized buffers are not allowed");
+        exit(1);
+    }
+
     while (sz) {
         hwaddr len = sz;