linux-kernel - Re: [PATCH] kbuild: treat char as always signed

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Message-ID: <202210191209.919149F4@keescook>
Date:   Wed, 19 Oct 2022 12:11:41 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Segher Boessenkool <segher@...nel.crashing.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-toolchains@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] kbuild: treat char as always signed

On Wed, Oct 19, 2022 at 11:56:00AM -0700, Linus Torvalds wrote:
> Hundreds and hundreds of that atomic_try_cmpxchg_acquire(), for
> example. And they might be trivial to fix (it might be similar to the
> fortify-string.h one where it's just a header file that generates most
> of them in one single place), but with all the ones that are just
> clearly the compiler being silly, they aren't really even worth
> looking at.

Yeah, I've had to fight these casts in fortify-string.h from time to
time. I'd love to see the patch you used -- I bet it would keep future
problems at bay.

-- 
Kees Cook