linux-kernel - Re: [PATCH 0/6] slab: Provide full coverage for __alloc

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Date:   Tue, 29 Nov 2022 12:24:32 +0000
From:   Conor Dooley <conor.dooley@...rochip.com>
To:     Kees Cook <keescook@...omium.org>
CC:     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 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.

Thanks,
Conor.

> Kees Cook (6):
>   slab: Clean up SLOB vs kmalloc() definition
>   slab: Remove special-casing of const 0 size allocations
>   slab: Provide functional __alloc_size() hints to kmalloc_trace*()
>   string: Add __realloc_size hint to kmemdup()
>   driver core: Add __alloc_size hint to devm allocators
>   kunit/fortify: Validate __alloc_size attribute results
> 
>  include/linux/device.h         |   7 +-
>  include/linux/fortify-string.h |   2 +-
>  include/linux/slab.h           |  36 ++---
>  include/linux/string.h         |   2 +-
>  lib/Makefile                   |   1 +
>  lib/fortify_kunit.c            | 255 +++++++++++++++++++++++++++++++++
>  mm/slab_common.c               |  14 ++
>  7 files changed, 296 insertions(+), 21 deletions(-)
> 
> -- 
> 2.34.1
> 
>