linux-kernel - Re: [PATCH] kconfig: Sanitize make randconfig generated .config

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Date:   Sat, 1 Feb 2020 14:15:52 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Vincenzo Frascino <vincenzo.frascino@....com>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kconfig: Sanitize make randconfig generated .config

On Sat, Feb 1, 2020 at 12:12 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> Hi.
>
>
> On Wed, Jan 22, 2020 at 7:03 PM Vincenzo Frascino
> <vincenzo.frascino@....com> wrote:
> >
> > "make randconfig" calculates the probability of a tristate option (yes,
> > mod, no) based on srand()/rand() and can be fed with a seed.
> > At the last step of randconfig some option are chosen randomly and their
> > tristate set based on similar mechanism.
> > After this passage the resulting .config is not sanitized, hence it
> > might result in an inconsistent set of options being selected.
> >
> > This was noticed on arm64 using KCONFIG_SEED=0x40C5E904. During
> > randomize_choice_values() CONFIG_BIG_ENDIAN is enabled. Since CONFIG_EFI
> > was enabled at a previous step, and depends on !CONFIG_BIG_ENDIAN the
> > resulting .config is inconsistent.
> >
> > Fix the issue making sure that randconfig sanitizes the generated
> > .config as a last step.
> >
> > Cc: Masahiro Yamada <masahiroy@...nel.org>
> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
> > ---
> >  scripts/kconfig/conf.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
> > index 1f89bf1558ce..c0fcaa4e9762 100644
> > --- a/scripts/kconfig/conf.c
> > +++ b/scripts/kconfig/conf.c
> > @@ -654,6 +654,11 @@ int main(int ac, char **av)
> >         case randconfig:
> >                 /* Really nothing to do in this loop */
> >                 while (conf_set_all_new_symbols(def_random)) ;
> > +               /*
> > +                * .config at this point might contain
> > +                * incompatible options. Sanitize it.
> > +                */
> > +               sym_clear_all_valid();
>
> Thanks for the report, but clearing
> all the valid flags is a big hammer.
> I do not think it is a proper fix.
>
>
> I checked the code, and I noticed the root cause of
> this bug.
>
> I will send a different patch later.


I think this is a more correct fix-up:
https://patchwork.kernel.org/patch/11360945/


-- 
Best Regards
Masahiro Yamada