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>
This commit is contained in:
Prasad J Pandit 2016-07-27 21:07:56 +05:30 committed by Michael S. Tsirkin
parent 9a4c0e220d
commit 1e7aed7014

View File

@ -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;