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Date:   Tue, 20 Feb 2018 11:26:28 -0500 (EST)
From:   Nicolas Pitre <nicolas.pitre@linaro.org>
To:     Richard Weinberger <richard@nod.at>
cc:     Masahiro Yamada <yamada.masahiro@socionext.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>, david@sigma-star.at,
        kbuild-all@01.org, Sam Ravnborg <sam@ravnborg.org>,
        Arnaud Lacombe <lacombar@gmail.com>,
        Nick Bowler <nbowler@elliptictech.com>,
        Michal Marek <mmarek@suse.cz>,
        Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH v2] kbuild: Don't source kernel config
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On Tue, 20 Feb 2018, Richard Weinberger wrote:

> An alternate approach would be this:
> diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
> index 5c12dc91ef34..ff0a7c62344b 100644
> --- a/scripts/kconfig/confdata.c
> +++ b/scripts/kconfig/confdata.c
> @@ -161,6 +161,13 @@ static int conf_set_sym_val(struct symbol *sym, int def, 
> int def_flags, char *p)
>  	case S_STRING:
>  		if (*p++ != '"')
>  			break;
> +
> +		p2 = strpbrk(p, "`$");
> +		if (p2 && !(p2[0] == '$' && p2[1] != '(')) {
> +			conf_warning("string contains forbidden characters");
> +			return 1;
> +		}
> +
>  		for (p2 = p; (p2 = strpbrk(p2, "\"\\")); p2++) {
>  			if (*p2 == '"') {
>  				*p2 = 0;
> 
> That way the conf tool will sanitize the .config before shell scripts will 
> source it.

Looks like a much saner approach to me indeed.


Nicolas