[Qemu-devel] [PATCH] display: virtio-gpu-3d: check virgl capabilities max_size

[P J P <ppandit@redhat.com>]

From: Prasad J Pandit <pjp@fedoraproject.org>

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>
---
 hw/display/virtio-gpu-3d.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/hw/display/virtio-gpu-3d.c b/hw/display/virtio-gpu-3d.c
index 758d33a..fbfb39f 100644
--- a/hw/display/virtio-gpu-3d.c
+++ b/hw/display/virtio-gpu-3d.c
@@ -371,11 +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);
-
-    resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
-    virgl_renderer_fill_caps(gc.capset_id,
-                             gc.capset_version,
-                             (void *)resp->capset_data);
+    if (max_size) {
+        resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
+        virgl_renderer_fill_caps(gc.capset_id,
+                                 gc.capset_version,
+                                 (void *)resp->capset_data);
+    }
     virtio_gpu_ctrl_response(g, cmd, &resp->hdr, sizeof(*resp) + max_size);
     g_free(resp);
 }
-- 
2.9.3