On Tue, Feb 3, 2026 at 3:42 PM Arnd Bergmann <[email protected]> wrote: > > On Tue, Feb 3, 2026, at 15:13, Eugenio Perez Martin wrote: > > On Tue, Feb 3, 2026 at 11:35 AM Michael S. Tsirkin <[email protected]> wrote: > >> Along with it or no, surely before the release. > >> Given 32 on 64 with this apparently has been broken forever, > >> I will merge this just based on even you did not bother testing compat, I > >> am > >> inclined to say I am merging this but not rebasing because > >> of this. > >> > >> Oh and we got lucky this didn't leak kernel stack info. > >> > >> Eugenio, note for the future: please help make sure UAPI > >> structs do not have hidden padding. > >> > > > > Sure. I'm trying to find an automatic way to check for this but with > > no luck :(. Arnd, did you use some tool for this or you just found it > > by visual inspection? I'm trying pahole and -Wpadded but the output > > includes a lot of struct not related to uapi. > > > > I guess it is possible to filter it with some clang or awk machinery, > > but I'm asking in case I avoid developing something already existing. > > I have the patch series, but it's not quite ready for submission. > In total, I annotated around 10% of the structure definitions > (500 files) in include/uapi/ to shut up -Wpadded for all the > existing structures with holes in them. > > In the end I turn on the check with > > --- a/usr/include/Makefile > +++ b/usr/include/Makefile > @@ -6,7 +6,7 @@ > # > # -std=c90 (equivalent to -ansi) catches the violation of those. > # We cannot go as far as adding -Wpedantic since it emits too many warnings. > -UAPI_CFLAGS := -std=c90 -Werror=implicit-function-declaration > +UAPI_CFLAGS := -std=c90 -Werror=implicit-function-declaration -Werror=padded > > # when cross-compiling with a minimal toolchain, use nolibc headers > UAPI_CFLAGS += -I$(srctree)/tools/include/nolibc/ > > which of course warns for all the existing holes. I will continue > to send fixes for new instances in the meantime, as I'm testing > linux-next. >
Got it, to develop something in parallel would be to duplicate work then. Looking forward to it then, thank you very much!
