linux-kernel - Re: [PATCH 2/2] kconfig: Deny command substitution in string values

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Message-ID: <1402570794.96583.1632295660867.JavaMail.zimbra@nod.at>
Date:   Wed, 22 Sep 2021 09:27:40 +0200 (CEST)
From:   Richard Weinberger <richard@....at>
To:     Boris Kolpackov <boris@...esynthesis.com>
Cc:     masahiroy@...nel.org, linux-kernel <linux-kernel@...r.kernel.org>,
        linux-kbuild@...r.kernel.org
Subject: Re: [PATCH 2/2] kconfig: Deny command substitution in string values

Boris,

----- Ursprüngliche Mail -----
> Von: "Boris Kolpackov" <boris@...esynthesis.com>
> An: "richard" <richard@....at>
> CC: masahiroy@...nel.org, "linux-kernel" <linux-kernel@...r.kernel.org>, linux-kbuild@...r.kernel.org
> Gesendet: Mittwoch, 22. September 2021 09:17:44
> Betreff: Re: [PATCH 2/2] kconfig: Deny command substitution in string values

> Richard Weinberger <richard@....at> writes:
> 
>> The post processed .config file will get included in shell
>> and makefiles.
> 
> That depends on who you ask: a number of projects other than the
> Linux kernel use kconfig for configuration and some of them do
> neither of those. I also don't believe the Linux kernel sources
> .config in shell (but I may be wrong).

See below.

> 
>> So make sure that a string does not contain
>> symbols that allow command substitution.
>> If such a malformed string is found, return empty string
>> and report it.
> 
> So effectively it's now impossible to include ` or $ in kconfig
> string values. Seems like a major, backwards-incompatible
> restriction.

Do you have a working example?
Since the config is sourced in the scripts/setlocalversion it will
not work correctly anyway.

> I think if this is really desired, then it should be re-done with
> escaping (similar to ") rather than outright banning inconvenient
> characters.

Escaping is not so easy since the very same content is included
in shell scripts (sertlocalversion), in Makefiles and in C files.
At least I didn't find find a good way to escape these characters
such that all three programming environments will accept it.

Thanks,
//richard