Memory Safety for Embedded Devices with nesCheck

Abstract

Applications for TinyOS, a popular operating system for embedded systems and wireless sensor networks, are written in nesC, a C dialect prone to the same type and memory safety vulnerabilities as C. While availability and integrity are critical requirements, the distributed and concurrent nature of such applications, combined with the intrinsic unsafety of the language, makes those security goals hard to achieve. Traditional memory safety techniques cannot be applied, due to the strict platform constraints and hardware differences of embedded systems. We design nesCheck, an approach that combines static analysis and dynamic checking to automatically enforce memory safety on nesC programs without requiring source modifications. nesCheck analyzes the source code, identifies the minimal conservative set of vulnerable pointers, finds static memory bugs, and instruments the code with the required dynamic runtime checks. Our prototype extends the existing TinyOS compiler toolchain with LLVM-based passes. Our evaluation shows that nesCheck effectively and efficiently enforces memory protection, catching all memory errors with an overhead of 0.84% on energy, 5.3% on code size, up to 8.4% on performance, and 16.7% on RAM.