ViK: practical mitigation of temporal memory safety violations through object ID inspection

ABSTRACTTemporal memory safety violations, such as use-after-free (UAF) vulnerabilities, are a critical security issue for software written in memory-unsafe languages such as C and C++. In this paper, we introduce ViK, a novel, lightweight, and widely applicable runtime defense that can protect both operating system (OS) kernels and user-space applications against temporal memory safety violations. ViK performs object ID inspection, where it assigns a random identifier to every allocated object and stores the identifier in the unused bits of the corresponding pointer. When the pointer is used, ViK inspects the value of a pointer before dereferencing, ensuring that the pointer still references the original object. To the best of our knowledge, this is the first mitigation against temporal memory safety violations that scales to OS kernels. We evaluated the software prototype of ViK on Android and Linux kernels and observed runtime overhead of around 20%. Also, we evaluated a hardware-assisted prototype of ViK on Android kernel, where the runtime overhead was as low as 2%.