TrEKer: Tracing error propagation in operating system kernels

Modern operating systems (OSs) consist of numerous interacting components, many of which are developed and maintained independently of one another. In monolithic systems, the boundaries of and interfaces between such components are not strictly enforced at runtime. Therefore, faults in individual components may directly affect other parts of the system in various ways. Software fault injection (SFI) is a testing technique to assess the resilience of a software system in the presence of faulty components. Unfortunately, SFI tests of OSs are inconclusive if they do not lead to observable failures, as corruptions of the internal software state may not be visible at its interfaces and, yet, affect the subsequent execution of the OS beyond the duration of the test. In this paper we present TREKER, a fully automated approach for identifying how faulty OS components affect other parts of the system. TREKER combines static and dynamic analyses to achieve efficient tracing on the granularity of memory accesses. We demonstrate TrEKer's ability to support SFI oracles by accurately tracing the effects of faults injected into three widely used Linux kernel modules.