Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230407215406.768464-1-ndesaulniers@google.com>
 <168435014337.2056649.7592777028793700479.b4-ty@chromium.org>
 <CAFP8O3L_RsaTMJvT7hmjD6ON49uob9Fb4mWg8ZUav_Y-FCgTMA@mail.gmail.com>
 <CAFP8O3JivZh+AAV7N90Nk7U2BHRNST6MRP0zHtfQ-Vj0m4+pDA@mail.gmail.com> <202305171215.7C58897@keescook>
In-Reply-To: <202305171215.7C58897@keescook>
From:   Fangrui Song <maskray@google.com>
Date:   Wed, 17 May 2023 12:22:57 -0700
Message-ID: <CAFP8O3JuPsCTgTXLkQpoy9WZG2jPxyisCjWhsB7yqJ-D9nA=OA@mail.gmail.com>
Subject: Re: [PATCH] ubsan: remove cc-option test for UBSAN_TRAP
To:     Kees Cook <keescook@chromium.org>
Cc:     ndesaulniers@google.com, masahiroy@kernel.org,
        linux-kbuild@vger.kernel.org, nathan@kernel.org,
        linux-hardening@vger.kernel.org, jpoimboe@kernel.org,
        llvm@lists.linux.dev, mbenes@suse.cz, linux-kernel@vger.kernel.org,
        trix@redhat.com, peterz@infradead.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Wed, May 17, 2023 at 12:16=E2=80=AFPM Kees Cook <keescook@chromium.org> =
wrote:
>
> On Wed, May 17, 2023 at 12:09:35PM -0700, Fangrui Song wrote:
> > On Wed, May 17, 2023 at 12:08=E2=80=AFPM Fangrui Song <maskray@google.c=
om> wrote:
> > >
> > > On Wed, May 17, 2023 at 12:02=E2=80=AFPM Kees Cook <keescook@chromium=
.org> wrote:
> > > >
> > > > On Fri, 7 Apr 2023 14:54:06 -0700, Nick Desaulniers wrote:
> > > > > -fsanitize-undefined-trap-on-error has been supported since GCC 5=
.1 and
> > > > > Clang 3.2.  The minimum supported version of these according to
> > > > > Documentation/process/changes.rst is 5.1 and 11.0.0 respectively.=
 Drop
> > > > > this cc-option check.
> > > > >
> > > > >
> > > >
> > > > Applied to for-next/hardening, thanks!
> > > >
> > > > [1/1] ubsan: remove cc-option test for UBSAN_TRAP
> > > >       https://git.kernel.org/kees/c/08e4044243a6
> > > >
> > > > --
> > > > Kees Cook
> > > >
> > > >
> > >
> > > For this -fsanitize-undefined-trap-on-error, I think we need a v2 pat=
ch that
> > > tries -fsanitize-trap=3Dall as well.
> >
> > Correction: -fsanitize-trap=3Dundefined
> >
> > > -fsanitize-undefined-trap-on-error has been deprecated in Clang for 8
> > > years, and at some point we will remove the option.
> > >
> > > GCC implements -fsanitize-trap=3Dall later, but
> > > -fsanitize-undefined-trap-on-error is documented as deprecated as
> > > well.
>
> Right now all the compilers support the old way, and I'd rather remove a
> cc-option call than add two. :)
>
> --
> Kees Cook

Hmm, this gives Clang developers a disadvantage... Anyone who removes
Clang's -fsanitize-undefined-trap-on-error (or give it a warning
before removal) will probably face complaints from kernel
developers...


--=20
=E5=AE=8B=E6=96=B9=E7=9D=BF