You should be able to trigger the DoS issue with your custom rules by changing 'http://googleadservices.com http://googleadservices.com' to 'http://facebook.com

You should be able to trigger the DoS issue with your custom rules by changing 'http://googleadservices.com http://googleadservices.com' to 'http://facebook.com http://facebook.com' in the uMatrix POC code. You will also be affected if you have any of the filter lists enabled on the "Assets" tab in the uMatrix dashboard. There may be other ways of triggering the bug, too--those are just two of the more obvious ones.