The 'res->iov' will be leaked if the guest trigger following sequences:

	virgl_cmd_create_resource_2d
	virgl_resource_attach_backing
	virgl_cmd_resource_unref

This patch fixes this.

Fixes: CVE-2021-3544
Reported-by: Li Qiang <liq3ea@163.com>
virtio-gpu fix: 5e8e3c4c75 ("virtio-gpu: fix resource leak
in virgl_cmd_resource_unref"

Signed-off-by: Li Qiang <liq3ea@163.com>
---
 contrib/vhost-user-gpu/virgl.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/contrib/vhost-user-gpu/virgl.c b/contrib/vhost-user-gpu/virgl.c
index 6a332d601f..c669d73a1d 100644
--- a/contrib/vhost-user-gpu/virgl.c
+++ b/contrib/vhost-user-gpu/virgl.c
@@ -108,9 +108,16 @@ virgl_cmd_resource_unref(VuGpu *g,
                          struct virtio_gpu_ctrl_command *cmd)
 {
     struct virtio_gpu_resource_unref unref;
+    struct iovec *res_iovs = NULL;
+    int num_iovs = 0;
 
     VUGPU_FILL_CMD(unref);
 
+    virgl_renderer_resource_detach_iov(unref.resource_id,
+                                       &res_iovs,
+                                       &num_iovs);
+    g_free(res_iovs);
+
     virgl_renderer_resource_unref(unref.resource_id);
 }
 
-- 
2.25.1