display: virtio-gpu-3d: check virgl capabilities max_size

Virtio GPU device while processing 'VIRTIO_GPU_CMD_GET_CAPSET'
command, retrieves the maximum capabilities size to fill in the
response object. It continues to fill in capabilities even if
retrieved 'max_size' is zero(0), thus resulting in OOB access.
Add check to avoid it.

Reported-by: Zhenhao Hong <zhenhaohong@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 20161214070156.23368-1-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/hw/display/virtio-gpu-3d.c b/hw/display/virtio-gpu-3d.c
index 23f39de94d3a4e355673f14cbced5aed7e312e87..e29f099bd57136bb82557c90e4c7b18ef32f550e 100644 (file)
--- a/hw/display/virtio-gpu-3d.c
+++ b/hw/display/virtio-gpu-3d.c
@@ -371,8 +371,12 @@ static void virgl_cmd_get_capset(VirtIOGPU *g,
 
     virgl_renderer_get_cap_set(gc.capset_id, &max_ver,
                                &max_size);
-    resp = g_malloc(sizeof(*resp) + max_size);
+    if (!max_size) {
+        cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
+        return;
+    }
 
+    resp = g_malloc(sizeof(*resp) + max_size);
     resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
     virgl_renderer_fill_caps(gc.capset_id,
                              gc.capset_version,