Enforcing Forward-Edge Control-Flow Integrity

Constraining dynamic control transfers is a common tech-nique for mitigating software vulnerabilities. This de-fense has been widely and successfully used to protect return addresses and stack data; hence, current attacks instead typically corrupt vtable and function pointers to subvert a forward edge (an indirect jump or call) in the control-flow graph. Forward edges can be protected us-ing Control-Flow Integrity (CFI) but, to date, CFI im-plementations have been research prototypes, based on impractical assumptions or ad hoc, heuristic techniques. To be widely adoptable, CFI mechanisms must be inte-grated into production compilers and be compatible with software-engineering aspects such as incremental compi-lation and dynamic libraries. This paper presents implementations of fine-grained, forward-edge CFI enforcement and analysis for GCC and LLVM that meet the above requirements. An analysis and evaluation of the security, performance, and resource consumption of these mechanisms applied to the SPEC CPU2006 benchmarks and common benchmarks for the Chromium web browser show the practicality of our ap-proach: these fine-grained CFI mechanisms have signif-icantly lower overhead than recent academic CFI proto-types. Implementing CFI in industrial compiler frame-works has also led to insights into design tradeoffs and practical challenges, such as dynamic loading.