linux-kernel - Re: [PATCH v4 2/4] module: panic: Taint the kernel when selftest modules load

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Message-ID: <Yr91dWijROn4gyLl@bombadil.infradead.org>
Date:   Fri, 1 Jul 2022 15:30:13 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     David Gow <davidgow@...gle.com>
Cc:     Brendan Higgins <brendanhiggins@...gle.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        "Guilherme G . Piccoli" <gpiccoli@...lia.com>,
        Sebastian Reichel <sre@...nel.org>,
        John Ogness <john.ogness@...utronix.de>,
        Joe Fradley <joefradley@...gle.com>,
        Daniel Latypov <dlatypov@...gle.com>,
        kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        Aaron Tomlin <atomlin@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kbuild@...r.kernel.org
Subject: Re: [PATCH v4 2/4] module: panic: Taint the kernel when selftest
 modules load

On Fri, Jul 01, 2022 at 04:47:42PM +0800, David Gow wrote:
> Taint the kernel with TAINT_TEST whenever a test module loads, by adding
> a new "TEST" module property, and setting it for all modules in the
> tools/testing directory. This property can also be set manually, for
> tests which live outside the tools/testing directory with:
> MODULE_INFO(test, "Y");
> 
> Signed-off-by: David Gow <davidgow@...gle.com>
> ---
> 
> This patch is new in v4 of this series.
> 
> ---
>  kernel/module/main.c  | 8 ++++++++
>  scripts/mod/modpost.c | 3 +++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index fed58d30725d..f2ca0a3ee5e6 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -1988,6 +1988,14 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags)
>  	/* Set up license info based on the info section */
>  	set_license(mod, get_modinfo(info, "license"));
>  
> +	if (!get_modinfo(info, "test")) {
> +		if (!test_taint(TAINT_TEST))
> +			pr_warn("%s: loading test module taints kernel.\n",
> +				mod->name);

That seems pretty chatty, maybe just pr_warn_once() and make indicate
which is the first one? For kernel builds where their goal is to just
loop testing this will grow the kernel log without not much need.

  Luis

> +		add_taint_module(mod, TAINT_TEST, LOCKDEP_STILL_OK);
> +	}
> +
> +
>  	return 0;
>  }
>  
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 29d5a841e215..5937212b4433 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -2191,6 +2191,9 @@ static void add_header(struct buffer *b, struct module *mod)
>  
>  	if (strstarts(mod->name, "drivers/staging"))
>  		buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
> +
> +	if (strstarts(mod->name, "tools/testing"))
> +		buf_printf(b, "\nMODULE_INFO(test, \"Y\");\n");

Otherwise looks good, thanks for doing this!

Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>

  Luis