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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sat, 26 Mar 2022 12:29:57 -0700
Message-ID: <CAHk-=wjeGc-BjkDWTYkXzyQu-vf9EEujuT-6=U7Od0DvCUfb8w@mail.gmail.com>
Subject: Re: [GIT PULL] FORTIFY_SOURCE updates for v5.18-rc1
To:     Kees Cook <keescook@chromium.org>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        George Burgess IV <gbiv@google.com>,
        linux-hardening@vger.kernel.org, llvm@lists.linux.dev,
        Miguel Ojeda <ojeda@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>
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On Fri, Mar 25, 2022 at 3:03 PM Kees Cook <keescook@chromium.org> wrote:
>
> It looks like all the dependent trees with related buffer fixes have been
> merged (I was waiting for the scsi tree to get pulled). This has been
> in -next for almost 2 development cycles, and I did overnight build
> testing merged against your tree under the following combinations,
> with no new warnings (there is one Clang 14+ specific issue in
> drivers/net/ethernet/huawei/hinic that we're still tracking down as a
> likely compiler regression[1]):

So how much of this is _completely_ compile-time?

Right now it looks to me like FORTIFY_SOURCE ends up doing two things

 - added runtime checking based on compile-time sizes

 - compile-time errors

How hard would it be to separate the two issues out?

Because if all the compiler issues and warnings have been sorted out,
it sounds to me like the compile-time side could/should be done
unconditionally if there are no runtime downsides.

Hmm?

                Linus