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Message-ID: <202212010915.ADB7D298@keescook>
Date: Thu, 1 Dec 2022 09:15:34 -0800
From: Kees Cook <keescook@...omium.org>
To: Arnd Bergmann <arnd@...db.de>
Cc: "Conor.Dooley" <conor.dooley@...rochip.com>,
Vlastimil Babka <vbabka@...e.cz>,
David Gow <davidgow@...gle.com>,
Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Hyeonggon Yoo <42.hyeyoo@...il.com>,
Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
Guenter Roeck <linux@...ck-us.net>,
Andy Shevchenko <andriy.shevchenko@...el.com>,
Paolo Abeni <pabeni@...hat.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Tom Rix <trix@...hat.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-hardening@...r.kernel.org,
llvm@...ts.linux.dev
Subject: Re: [PATCH 0/6] slab: Provide full coverage for __alloc_size
attribute
On Tue, Nov 29, 2022 at 01:33:03PM +0100, Arnd Bergmann wrote:
> On Tue, Nov 29, 2022, at 13:24, Conor Dooley wrote:
> > On Tue, Nov 01, 2022 at 03:33:08PM -0700, Kees Cook wrote:
> >> Hi,
> >>
> >> This is a series to work around a deficiency in GCC (>=11) and Clang
> >> (<16) where the __alloc_size attribute does not apply to inlines. :(
> >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96503
> >>
> >> This manifests as reduced overflow detection coverage for many allocation
> >> sites under CONFIG_FORTIFY_SOURCE=y, where the allocation size was
> >> not actually being propagated to __builtin_dynamic_object_size(). In
> >> addition to working around the issue, expand use of __alloc_size (and
> >> __realloc_size) to more places and provide KUnit tests to validate all
> >> the covered allocator APIs.
> >
> > Hello Kees!
> >
> > It would appear that one of the macros you've added here is doing Bad
> > Things^TM to allmodconfig on RISC-V since the 22nd:
> >
> > ../lib/fortify_kunit.c: In function 'alloc_size_kmalloc_const_test':
> > ../lib/fortify_kunit.c:140:1: error: the frame size of 2384 bytes is
> > larger than 2048 bytes [-Werror=frame-larger-than=]
> > 140 | }
> > \
> > | ^
> > ../lib/fortify_kunit.c:209:1: note: in expansion of macro
> > 'DEFINE_ALLOC_SIZE_TEST_PAIR'
> > 209 | DEFINE_ALLOC_SIZE_TEST_PAIR(kmalloc)
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> > cc1: all warnings being treated as errors
> >
> > CONFIG_GCC_VERSION=110100
> > CONFIG_AS_VERSION=23700
> > CONFIG_LD_VERSION=23700
> >
> > The report came out of my CI (which I should have passed on sooner) so
> > I do not have anything other than stderr - I can get you anything else
> > you'd like/need though if you LMK.
>
> There is generally a conflict between kunit and the structleak
> gcc plugin, I think the Makefile needs a line like
>
> CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN)
Thanks for the report! I've taken Anders's patch for this now.
--
Kees Cook
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