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[Qemu-devel] [PATCH] virtio: check vring descriptor buffer length

From: P J P
Subject: [Qemu-devel] [PATCH] virtio: check vring descriptor buffer length
Date: Wed, 27 Jul 2016 21:07:56 +0530

From: Prasad J Pandit <address@hidden>

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 <address@hidden>
Signed-off-by: Prasad J Pandit <address@hidden>
 hw/virtio/virtio.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 30ede3d..8de896c 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -457,6 +457,11 @@ 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;

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