Re: [PATCH v1 6/6] bitfield: build kunit tests without structleak plugin

[Kees Cook]

On Fri, Sep 17, 2021 at 09:22:08AM +0200, Arnd Bergmann wrote:
> On Fri, Sep 17, 2021 at 8:11 AM Brendan Higgins
> <brendanhiggins@xxxxxxxxxx> wrote:
> >
> > From: Arnd Bergmann <arnd@xxxxxxxx>
> >
> > The structleak plugin causes the stack frame size to grow immensely:
> >
> > lib/bitfield_kunit.c: In function 'test_bitfields_constants':
> > lib/bitfield_kunit.c:93:1: error: the frame size of 7440 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
> >
> > Turn it off in this file.
> >
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> > Signed-off-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
> > ---
> >  lib/Makefile | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/Makefile b/lib/Makefile
> > index 5efd1b435a37c..c93c4b59af969 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -351,7 +351,7 @@ obj-$(CONFIG_OBJAGG) += objagg.o
> >  obj-$(CONFIG_PLDMFW) += pldmfw/
> >
> >  # KUnit tests
> > -CFLAGS_bitfield_kunit.o := $(call cc-option,-Wframe-larger-than=10240)
> > +CFLAGS_bitfield_kunit.o := $(call cc-option,-Wframe-larger-than=10240) $(DISABLE_STRUCTLEAK_PLUGIN)
> 
> I think the  $(call cc-option,-Wframe-larger-than=10240) needs to be dropped
> here. This was not in my original patch and it is definitely broken on
> all architectures
> with 8KB stack size or less if the function needs that much. What is the amount
> of actual stack usage you observe without this? If we still get a warning, then
> I think this needs to be fixed in the code.

With the frame-larger-than dropped:

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>


-- 
Kees Cook