On Wed, May 31, 2023 at 1:14 AM Kees Cook <keesc...@chromium.org> wrote: > > On Mon, May 29, 2023 at 04:50:45PM +0200, Miguel Ojeda wrote: > > Kees: what is the current stance on `[static N]` parameters? Something like: > > > > const char *kallsyms_lookup(unsigned long addr, > > unsigned long *symbolsize, > > unsigned long *offset, > > - char **modname, char *namebuf); > > + char **modname, char namebuf[static > > KSYM_NAME_LEN]); > > > > makes the compiler complain about cases like these (even if trivial): > > > > arch/powerpc/xmon/xmon.c:1711:10: error: array argument is too small; > > contains 128 elements, callee requires at least 512 > > [-Werror,-Warray-bounds] > > name = kallsyms_lookup(pc, &size, &offset, NULL, tmpstr); > > ^ ~~~~~~ > > ./include/linux/kallsyms.h:86:29: note: callee declares array > > parameter as static here > > char **modname, char namebuf[static KSYM_NAME_LEN]); > > ^ ~~~~~~~~~~~~~~~~~~~~~~ > > Wouldn't that be a good thing? (I.e. complain about the size mismatch?)
Yeah, I would say so (i.e. I meant it as a good thing). > > But I only see 2 files in the kernel using `[static N]` (from 2020 and > > 2021). Should something else be used instead (e.g. `__counted_by`), > > even if constexpr-sized?. > > Yeah, it seems pretty uncommon. I'd say traditionally arrays aren't > based too often, rather structs containing them. > > But ultimately, yeah, everything could gain __counted_by and friends in > the future. That would be nice! Cheers, Miguel
