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Date:   Wed, 19 Oct 2022 10:30:54 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Alexander Potapenko <glider@google.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, kasan-dev@googlegroups.com,
        linux-mm@kvack.org
Subject: Re: -Wmacro-redefined in include/linux/fortify-string.h
Message-ID: <202210191030.EC5C138E@keescook>
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 <CAG_fn=WYnfNHC3S1S=mCTKTnzL=UuH7Oz4W3HjsTXEQUtjrxtw@mail.gmail.com>
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On Wed, Oct 19, 2022 at 09:48:27AM -0700, Alexander Potapenko wrote:
> On Wed, Oct 19, 2022 at 8:37 AM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > Hi all,
> >
> > I am seeing the following set of warnings when building an x86_64
> > configuration that has CONFIG_FORTIFY_SOURCE=y and CONFIG_KMSAN=y:
> 
> I was also looking into this issue recently, because people start
> running into it: https://github.com/google/kmsan/issues/89
> 
> I have a solution that redefines __underlying_memXXX to __msan_memXXX
> under __SANITIZE_MEMORY__ in fortify-string.h and skips `#define
> memXXX __msan_memXXX` in string_64.h, making KMSAN kinda work with
> FORTIFY_SOURCE.

Oh good!

> Dunno if that's necessary though: KMSAN is a debugging tool anyway,
> and supporting it in fortify-string.h sounds excessive.

I'd much prefer letting them still work together.

-- 
Kees Cook