Tell You a Definite Answer: Whether Your Data is Tainted During Thread Scheduling

With the advent of multicore processors, there is a great need to write parallel programs to take advantage of parallel computing resources. However, due to the nondeterminism of parallel execution, the malware behaviors sensitive to thread scheduling are extremely difficult to detect. Dynamic taint analysis is widely used in security problems. By serializing a multithreaded execution and then propagating taint tags along the serialized schedule, existing dynamic taint analysis techniques lead to under-tainting with respect to other possible interleavings under the same input. In this paper, we propose an approach called DSTAM that integrates symbolic analysis and guided execution to systematically detect tainted instances on all possible executions under a given input. Symbolic analysis infers alternative interleavings of an executed trace that cover new tainted instances, and computes thread schedules that guide future executions. Guided execution explores new execution traces that drive future symbolic analysis. We have implemented a prototype as part of an educational tool that teaches secure C programming, where accuracy is more critical than efficiency. To the best of our knowledge, DSTAM is the first algorithm that addresses the challenge of taint analysis for multithreaded program under fixed inputs.