On Tue, Oct 1, 2019 at 1:17 AM Kees Cook <[email protected]> wrote: > On Mon, Sep 30, 2019 at 12:33:19PM +0200, Arnd Bergmann wrote: > > On Wed, Aug 28, 2019 at 7:38 PM Kees Cook <[email protected]> wrote: > > arch/x86/math-emu/reg_ld_str.c:88:2: error: ignoring return value of > > function declared with 'warn_unused_result' attribute > > [-Werror,-Wunused-result] > > __copy_from_user(sti_ptr, s, 10); > > ^~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~ > > arch/x86/math-emu/reg_ld_str.c:1129:2: error: ignoring return value of > > function declared with 'warn_unused_result' attribute > > [-Werror,-Wunused-result] > > __copy_from_user(register_base + offset, s, other); > > ^~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > arch/x86/math-emu/reg_ld_str.c:1131:3: error: ignoring return value of > > function declared with 'warn_unused_result' attribute > > [-Werror,-Wunused-result] > > __copy_from_user(register_base, s + other, offset); > > ^~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > What was the CONFIG for this? I didn't hit these in my build tests.
I saw three randconfig builds trigger it in one day, so not that common. https://pastebin.com/mUhbNEVR is one of them. > > Moreover, the same code also ignores the return value from most > > get_user()/put_user()/FPU_get_user()/FPU_put_user() calls, > > which have no warn_unused_result annotation (they are macros, > > but I think something could be done if we want to have that > > annotation to catch some of the other such users). > > It would certainly make sense to mark those as __must_check too... now > tracking this here for anyone that wants to take a stab at it: > https://github.com/KSPP/linux/issues/16 FWIW, I have not come up with a way to add the warning, but I did send a fix for the instances in the math-emu code: https://lore.kernel.org/lkml/[email protected]/ Arnd
