Control-flow integrity (CFI) is a set of techniques that make it more difficult for attackers to hijack indirect jumps to exploit a system. The Linux kernel has supported forward-edge CFI (which protects indirect function calls) since 2020, with the most recent implementation of the feature introduced in 2022. That version avoids the overhead introduced by the earlier approach by using a compiler flag (-fsanitize=kcfi) that is present in Clang but not in GCC. Now, Kees Cook has a patch set adding that support to GCC that looks likely to land in GCC 17.