The reported memory leak should have been spotted by make memcheck But it wasn't. Keeping the tests for better coverage.
The random buffer handed over to the test function was too small and the remaining bytes were generated by the default (platform dependant) function.
The main goal with these tests is to test the bug in question and they are not meant to test the entire PKCS#1 v1.5 behaviour. To achieve full test coverage, further test cases are needed.