On Thu, May 18, 2023 at 12:47:41AM +0100, Sam James wrote: > > Kees Cook <keescook@xxxxxxxxxxxx> writes: > > > The -fstrict-flex-arrays=3 option is now available with the release > > of GCC 13[1] and Clang 16[2]. This feature instructs the compiler to > > treat only C99 flexible arrays as dynamically sized for the purposes of > > object size calculations. In other words, the ancient practice of using > > 1-element arrays, or the GNU extension of using 0-sized arrays, as a > > dynamically sized array is disabled. This allows CONFIG_UBSAN_BOUNDS, > > CONFIG_FORTIFY_SOURCE, and other object-size aware features to behave > > unambiguously in the face of trailing arrays: only C99 flexible arrays > > are considered to be dynamically sized. > > > > Enabling this will help track down any outstanding cases of fake > > flexible arrays that need attention in kernel code. > > > > [1] https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html#index-fstrict-flex-arrays > > [2] https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fstrict-flex-arrays > > > > Maybe link to https://people.kernel.org/kees/bounded-flexible-arrays-in-c as well > just in case some confused soul ends up bisecting to this but doesn't > get the problem? > > Not really required though, just a thought I had. Ah yeah, good idea! :) -- Kees Cook
