linux-kernel - Re: [PATCH v1 2/6] iio/test-format: build kunit tests without structleak plugin

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Date:   Wed, 29 Sep 2021 13:50:41 -0700
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     shuah@...nel.org, davidgow@...gle.com, arnd@...db.de,
        rafael@...nel.org, jic23@...nel.org, lars@...afoo.de,
        ulf.hansson@...aro.org, andreas.noever@...il.com,
        michael.jamet@...el.com, mika.westerberg@...ux.intel.com,
        yehezkelshb@...il.com, masahiroy@...nel.org,
        michal.lkml@...kovi.net, ndesaulniers@...gle.com,
        linux-kselftest@...r.kernel.org, kunit-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        gregkh@...uxfoundation.org, linux-iio@...r.kernel.org,
        linux-mmc@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-hardening@...r.kernel.org, linux-kbuild@...r.kernel.org
Subject: Re: [PATCH v1 2/6] iio/test-format: build kunit tests without
 structleak plugin

On Fri, Sep 17, 2021 at 8:54 AM Kees Cook <keescook@...omium.org> wrote:
>
> On Thu, Sep 16, 2021 at 11:11:00PM -0700, Brendan Higgins wrote:
> > The structleak plugin causes the stack frame size to grow immensely when
> > used with KUnit:
> >
> > ../drivers/iio/test/iio-test-format.c: In function ‘iio_test_iio_format_value_fixedpoint’:
> > ../drivers/iio/test/iio-test-format.c:98:1: warning: the frame size of 2336 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> >
> > Turn it off in this file.
>
> Given that these are all for KUnit tests, is it possible there are going
> to be other CONFIGs that will interact poorly (e.g. KASAN)? Maybe there
> needs to be a small level of indirection with something like:

I don't think so. KASAN actually uses KUnit to test it, and we have
experimented running KASAN alongside other KUnit tests for added
protection and results have looked good.

I would be surprised if there are other CONFIGs other than things
dealing with stack size that don't like KUnit.

> DISABLE_UNDER_KUNIT := $(DISABLE_STRUCTLEAK_PLUGIN)
> export DISABLE_UNDER_KUNIT
>
> then all of these become:
>
> +CFLAGS_iio-test-format.o += $(DISABLE_UNDER_KUNIT)
>
> Either way, I think these are fine to add.

I like your suggestion if we find other configs that don't like KUnit,
but I don't think we have seen any others so far, so I think I will
keep it as it is for now.

> Reviewed-by: Kees Cook <keescook@...omium.org>
>
>
> >
> > Co-developed-by: Arnd Bergmann <arnd@...db.de>
> > Signed-off-by: Brendan Higgins <brendanhiggins@...gle.com>
> > ---
> >  drivers/iio/test/Makefile | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/iio/test/Makefile b/drivers/iio/test/Makefile
> > index f1099b4953014..467519a2027e5 100644
> > --- a/drivers/iio/test/Makefile
> > +++ b/drivers/iio/test/Makefile
> > @@ -5,3 +5,4 @@
> >
> >  # Keep in alphabetical order
> >  obj-$(CONFIG_IIO_TEST_FORMAT) += iio-test-format.o
> > +CFLAGS_iio-test-format.o += $(DISABLE_STRUCTLEAK_PLUGIN)
> > --
> > 2.33.0.464.g1972c5931b-goog
> >
>
> --
> Kees Cook