Messages in this thread | | | From | Arnd Bergmann <> | Date | Mon, 30 Sep 2019 12:33:19 +0200 | Subject | Re: [PATCH] uaccess: Add missing __must_check attributes |
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On Wed, Aug 28, 2019 at 7:38 PM Kees Cook <keescook@chromium.org> wrote: > > The usercopy implementation comments describe that callers of the > copy_*_user() family of functions must always have their return values > checked. This can be enforced at compile time with __must_check, so add > it where needed. > > Signed-off-by: Kees Cook <keescook@chromium.org>
I can't find any other reports, so I'd point out here that this found what looks like a bug in the x86 math-emu code:
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); ^~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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).
Arnd
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