PointerChecker: Tag-Based and Hardware-Assisted Memory Safety against Memory Corruption

Abstract

The exploitation of memory corruption continues to be a major threat to computer software and systems. Enforcing memory safety can stop all memory corruption exploits. Unfortu-nately, existing approaches for memory safety either suffer from high-performance overhead or have poor source compatibility. A compromise is only to detect spatial violations to get a trade-off between performance and security. However, temporal violations are still preferably targeted with the improvement of boundary checks. In this paper, we propose a lightweight solution, called PointerChecker, a complete memory safety architecture based on tagged memory. We design a 2-bit tag to represent four different memory states to protect both spatial and temporal safety. Besides, we design tag-based pointer metadata representations to reduce the storage of pointer metadata and the overhead of runtime checking. Combining them, we can successfully identify the memory safety violations at runtime. Based on LLVM infrastructure and LowRISC architecture, we implement the prototype with lightweight hardware extensions. The evaluation results show that the average performance overhead is 8.42%, and PointerChecker can provide source compatibility and strong security.