linux-hardening - Re: [PATCH] ubsan: remove cc-option test for UBSAN

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Message-ID: <6436ca47.a70a0220.e83cf.adf4@mx.google.com>
Date:   Wed, 12 Apr 2023 08:12:06 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Fangrui Song <maskray@...gle.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        linux-hardening@...r.kernel.org, Tom Rix <trix@...hat.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Miroslav Benes <mbenes@...e.cz>, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, linux-kbuild@...r.kernel.org
Subject: Re: [PATCH] ubsan: remove cc-option test for UBSAN_TRAP

On Tue, Apr 11, 2023 at 05:12:24PM -0700, Fangrui Song wrote:
> On Fri, Apr 7, 2023 at 2:58 PM Nathan Chancellor <nathan@...nel.org> wrote:
> >
> > On Fri, Apr 07, 2023 at 02:54:06PM -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.
> > >
> > > Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
> >
> > Reviewed-by: Nathan Chancellor <nathan@...nel.org>
> >
> > As an aside, we should really consider having some standard format of
> > comment around cc-option checks so that we can easily remove them when
> > they become stale...
> >
> > > ---
> > > Masahiro, Kees: get_maintainer.pl leaves much to be desired for this
> > > file. Can one of you please pick this up?
> > >
> > >  lib/Kconfig.ubsan | 1 -
> > >  1 file changed, 1 deletion(-)
> > >
> > > diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
> > > index fd15230a703b..0e7ad0782399 100644
> > > --- a/lib/Kconfig.ubsan
> > > +++ b/lib/Kconfig.ubsan
> > > @@ -15,7 +15,6 @@ if UBSAN
> > >  config UBSAN_TRAP
> > >       bool "On Sanitizer warnings, abort the running kernel code"
> > >       depends on !COMPILE_TEST
> > > -     depends on $(cc-option, -fsanitize-undefined-trap-on-error)
> > >       help
> > >         Building kernels with Sanitizer features enabled tends to grow
> > >         the kernel size by around 5%, due to adding all the debugging
> > > --
> > > 2.40.0.577.gac1e443424-goog
> > >
> >
> 
> -fsanitize-undefined-trap-on-error is a legacy option from 2013 when
> -fcatch-undefined-behavior instead of -fsanitize=undefined enabled
> UBSan.
> On the Clang side, http://reviews.llvm.org/D10464 added
> -fsanitize-trap= in June 2015.
> It's best to use -fsanitize-trap=undefined and avoid uses of
> -fsanitize-undefined-trap-on-error.

But that's Clang-only. -fsanitize-undefined-trap-on-error works for both
GCC and Clang.

-- 
Kees Cook