Abstract In VeriFuzz 1.4, we implemented two new techniques for checking Non-termination and Termination. VeriFuzz 1.4 won the Termination category of SV-COMP 2023.

Unintended non-termination of programs could lead to attacks such as Denial-of-Service(DoS). Current testing techniques are not geared to detect such errors. Towards this, we present FuzzNT, a hybrid testing technique to check non-termination of C programs by combining Coverage Guided Fuzzing (CGF) and abstract interpretation based static analysis. Given a program P and the coverage test inputs generated using CGF, P is transformed into a set of specialized programs, each of which under-approximates P. Abstract interpretation is then used to check each of these smaller programs for non-termination. The key advantage of this approach for checking non-termination is that it reuses the test case corpus created during software development and maintenance. Our preliminary experimental evaluation of FuzzNT shows highly promising results.