From: Daniel Latypov <dlatypov@google.com>
To: David Gow <davidgow@google.com>
Cc: Brendan Higgins <brendanhiggins@google.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Kees Cook <keescook@chromium.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Greg KH <gregkh@linuxfoundation.org>,
Luis Chamberlain <mcgrof@kernel.org>,
"Guilherme G . Piccoli" <gpiccoli@igalia.com>,
Sebastian Reichel <sre@kernel.org>,
John Ogness <john.ogness@linutronix.de>,
Joe Fradley <joefradley@google.com>,
KUnit Development <kunit-dev@googlegroups.com>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jani Nikula <jani.nikula@linux.intel.com>,
Lucas De Marchi <lucas.demarchi@intel.com>,
Aaron Tomlin <atomlin@redhat.com>,
linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: [PATCH v3 2/3] kunit: Taint the kernel when KUnit tests are run
Date: Sat, 14 May 2022 12:25:24 -0700 [thread overview]
Message-ID: <CAGS_qxqFEcw=28FxbMMtEcjqcsgFHXV6Td+uTgDj32Z=PiQJkA@mail.gmail.com> (raw)
In-Reply-To: <CABVgOS=gTznLFBTZbmNH7AFDnr7O70mWR9v4q6sDA7q04fKT=Q@mail.gmail.com>
On Fri, May 13, 2022 at 8:04 PM David Gow <davidgow@google.com> wrote:
> Hmm... thinking about it, I think it might be worth not tainting if 0
> suites run, but tainting if 0 tests run.
>
> If we taint even if there are no suites present, that'll make things
> awkward for the "build KUnit in, but not any tests" case: the kernel
> would be tainted regardless. Given Android might be having the KUnit
Actually, this is what the code does right now. I was wrong.
If there are 0 suites => not tainted.
If there are 0 tests in the suites => tainted.
For kunit being built in, it first goes through this func
206 static void kunit_exec_run_tests(struct suite_set *suite_set)
207 {
208 struct kunit_suite * const * const *suites;
209
210 kunit_print_tap_header(suite_set);
211
212 for (suites = suite_set->start; suites <
suite_set->end; suites++)
213 __kunit_test_suites_init(*suites);
214 }
So for the "build KUnit in, but not any tests" case, you'll never
enter that for-loop.
Thus you'll never call __kunit_test_suites_init() => kunit_run_tests().
For module-based tests, we have the same behavior.
If there's 0 test suites, we never enter the second loop, so we never taint.
But if there's >0 suites, then we will, regardless of the # of test cases.
570 int __kunit_test_suites_init(struct kunit_suite * const * const suites)
571 {
572 unsigned int i;
573
574 for (i = 0; suites[i] != NULL; i++) {
575 kunit_init_suite(suites[i]);
576 kunit_run_tests(suites[i]);
577 }
578 return 0;
579 }
So this change should already work as intended.
> execution stuff built-in (but using modules for tests), it's probably
> worth not tainting there. (Though I think they have a separate way of
> disabling KUnit as well, so it's probably not a complete
> deal-breaker).
>
> The case of having suites but no tests should still taint the kernel,
> as suite_init functions could still run.
Yes, suite_init functions are the concern. I agree we should taint if
there are >0 suites but 0 test cases.
I don't think it's worth trying to be fancy and tainting iff there >0
test cases or a suite_init/exit function ran.
>
> Assuming that seems sensible, I'll send out a v4 with that changed.
Just to be clear: that shouldn't be necessary.
>
> > I wasn't quite sure where this applied, but I manually applied the changes here.
> > Without this patch, this command exits fine:
> > $ ./tools/testing/kunit/kunit.py run --kernel_args=panic_on_taint=0x40000
> >
> > With it, I get
> > [12:03:31] Kernel panic - not syncing: panic_on_taint set ...
> > [12:03:31] CPU: 0 PID: 1 Comm: swapper Tainted: G N
>
> This is showing both 'G' and 'N' ('G' being the character for GPL --
I just somehow missed the fact there was an 'N' at the end there.
Thanks, I thought I was going crazy. I guess I was just going blind.
Daniel
next prev parent reply other threads:[~2022-05-14 19:25 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-29 4:39 [PATCH] kunit: Taint kernel if any tests run David Gow
2022-04-29 7:09 ` Greg KH
2022-04-29 11:21 ` Jani Nikula
2022-04-29 11:41 ` Greg KH
2022-04-29 11:54 ` Jani Nikula
2022-04-29 12:07 ` Greg KH
2022-04-30 2:54 ` David Gow
2022-04-30 3:00 ` [PATCH v2] " David Gow
2022-04-30 5:50 ` Greg KH
2022-05-01 18:22 ` Luis Chamberlain
2022-05-01 18:24 ` Luis Chamberlain
2022-05-03 6:49 ` David Gow
2022-05-04 14:51 ` Luis Chamberlain
2022-05-04 16:25 ` Daniel Latypov
2022-05-04 18:46 ` Luis Chamberlain
2022-05-04 19:19 ` Daniel Latypov
2022-05-04 21:12 ` Luis Chamberlain
2022-05-05 5:57 ` Luis Chamberlain
2022-05-06 7:01 ` David Gow
2022-05-09 20:43 ` Luis Chamberlain
2022-05-13 8:32 ` [PATCH v3 1/3] panic: Taint kernel if tests are run David Gow
2022-05-13 15:35 ` Luis Chamberlain
2022-05-17 20:45 ` Brendan Higgins
2022-05-13 8:32 ` [PATCH v3 2/3] kunit: Taint the kernel when KUnit " David Gow
2022-05-13 15:36 ` Luis Chamberlain
2022-05-13 19:08 ` Daniel Latypov
2022-05-14 3:04 ` David Gow
2022-05-14 19:25 ` Daniel Latypov [this message]
2022-05-17 20:58 ` Brendan Higgins
2022-05-17 20:58 ` Brendan Higgins
2022-05-13 8:32 ` [PATCH v3 3/3] selftest: Taint kernel when test module loaded David Gow
2022-05-13 15:38 ` Luis Chamberlain
2022-05-14 8:34 ` David Gow
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