WatchdogLite: Hardware-Accelerated Compiler-Based Pointer Checking

Lack of memory safety in C is the root cause of a multitude of serious bugs and security vulnerabilities. Numerous software-only and hardware-based schemes have been proposed to enforce memory safety. Among these approaches, pointer-based checking, which maintains per-pointer metadata in a disjoint metadata space, has been recognized as providing comprehensive memory safety. Software approaches for pointer-based checking have high performance overheads. In contrast, hardware approaches introduce a myriad of hardware structures and widgets to mitigate those performance overheads. This paper proposes WatchdogLite, an ISA extension that provides hardware acceleration for a compiler implementation of pointer-based checking. This division of labor between the compiler and the hardware allows for hardware acceleration while using only preexisting architectural registers. By leveraging the compiler to identify pointers, perform check elimination, and insert the new instructions, this approach attains performance similar to prior hardware-intensive approaches without adding any hardware structures for tracking metadata.