Accurate Fault Injection with Concolic Testing

Fault injection, modifying the behavior of a program to facilitate the reproduction of hidden or rare problems, is an effective technique for detecting modularity violations in programs, such as missing error handling and implementationdependent behavior. However, conventional randomized fault injection suffers from poor coverage relative to the number of tests that it runs. In this work, we incorporate techniques from concolic testing to achieve better coverage in client code using a smaller number of tests. Techniques designed to keep false positive rates low are explored, and a number of simple bugs in deployed software are identified.