https://lists.gnu.org/archive/html/qemu-devel/2016-12/msg01903.html
https://bugs.gentoo.org/603444

From:	P J P
Subject:	[Qemu-devel] [PATCH] display: virtio-gpu-3d: check virgl capabilities max_size
Date:	Wed, 14 Dec 2016 12:31:56 +0530
From: Prasad J Pandit <address@hidden>

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 <address@hidden>
Signed-off-by: Prasad J Pandit <address@hidden>
---
 hw/display/virtio-gpu-3d.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/display/virtio-gpu-3d.c b/hw/display/virtio-gpu-3d.c
index 758d33a..6ceeba3 100644
--- a/hw/display/virtio-gpu-3d.c
+++ b/hw/display/virtio-gpu-3d.c
@@ -370,8 +370,12 @@ static void virgl_cmd_get_capset(VirtIOGPU *g,
 
     virgl_renderer_get_cap_set(gc.capset_id, &max_ver,
                                &max_size);
+    if (!max_size) {
+        cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
+        return;
+    }
+
     resp = g_malloc0(sizeof(*resp) + max_size);
-
     resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
     virgl_renderer_fill_caps(gc.capset_id,
                              gc.capset_version,
-- 
2.9.3