vmwgfx: corruption in vmw_event_fence_action_create()

We don't allocate enough data for this struct.  As soon as we start
modifying event->event on the next lines, then we're going beyond the
end of the memory we allocated.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/vmwgfx/vmwgfx_fence.c

@@ -1018,7 +1018,7 @@ int vmw_event_fence_action_create(struct drm_file *file_priv,
 	}
 
 
-	event = kzalloc(sizeof(event->event), GFP_KERNEL);
+	event = kzalloc(sizeof(*event), GFP_KERNEL);
 	if (unlikely(event == NULL)) {
 		DRM_ERROR("Failed to allocate an event.\n");
 		ret = -ENOMEM;