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From: Vlastimil Babka <vbabka@suse.cz>
To: Kees Cook <keescook@chromium.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Christoph Lameter" <cl@linux.com>,
	"Pekka Enberg" <penberg@kernel.org>,
	"David Rientjes" <rientjes@google.com>,
	"Joonsoo Kim" <iamjoonsoo.kim@lge.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Roman Gushchin" <roman.gushchin@linux.dev>,
	"Hyeonggon Yoo" <42.hyeyoo@gmail.com>,
	"Marco Elver" <elver@google.com>,
	linux-mm@kvack.org, "Ruhl, Michael J" <michael.j.ruhl@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Nick Desaulniers" <ndesaulniers@google.com>,
	"Alex Elder" <elder@kernel.org>,
	"Josef Bacik" <josef@toxicpanda.com>,
	"David Sterba" <dsterba@suse.com>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christian König" <christian.koenig@amd.com>,
	"Jesse Brandeburg" <jesse.brandeburg@intel.com>,
	"Daniel Micay" <danielmicay@gmail.com>,
	"Yonghong Song" <yhs@fb.com>, "Miguel Ojeda" <ojeda@kernel.org>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	linux-btrfs@vger.kernel.org, linux-media@vger.kernel.org,
	dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
	linux-fsdevel@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
	dev@openvswitch.org, x86@kernel.org, llvm@lists.linux.dev,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2 01/16] slab: Remove __malloc attribute from realloc functions
Date: Wed, 28 Sep 2022 23:39:06 +0200	[thread overview]
Message-ID: <d5cb63f4-b1f5-9862-c31c-c8c6c4cb41df@suse.cz> (raw)
In-Reply-To: <202209281011.66DD717D@keescook>

On 9/28/22 19:13, Kees Cook wrote:
> On Wed, Sep 28, 2022 at 09:26:15AM +0200, Geert Uytterhoeven wrote:
>> Hi Kees,
>>
>> On Fri, Sep 23, 2022 at 10:35 PM Kees Cook <keescook@chromium.org> wrote:
>>> The __malloc attribute should not be applied to "realloc" functions, as
>>> the returned pointer may alias the storage of the prior pointer. Instead
>>> of splitting __malloc from __alloc_size, which would be a huge amount of
>>> churn, just create __realloc_size for the few cases where it is needed.
>>>
>>> Additionally removes the conditional test for __alloc_size__, which is
>>> always defined now.
>>>
>>> Cc: Christoph Lameter <cl@linux.com>
>>> Cc: Pekka Enberg <penberg@kernel.org>
>>> Cc: David Rientjes <rientjes@google.com>
>>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>>> Cc: Andrew Morton <akpm@linux-foundation.org>
>>> Cc: Vlastimil Babka <vbabka@suse.cz>
>>> Cc: Roman Gushchin <roman.gushchin@linux.dev>
>>> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
>>> Cc: Marco Elver <elver@google.com>
>>> Cc: linux-mm@kvack.org
>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>
>> Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab:
>> Remove __malloc attribute from realloc functions") in next-20220927.
>>
>> Noreply@ellerman.id.au reported all gcc8-based builds to fail
>> (e.g. [1], more at [2]):
>>
>>      In file included from <command-line>:
>>      ./include/linux/percpu.h: In function ‘__alloc_reserved_percpu’:
>>      ././include/linux/compiler_types.h:279:30: error: expected
>> declaration specifiers before ‘__alloc_size__’
>>       #define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
>>                                    ^~~~~~~~~~~~~~
>>      ./include/linux/percpu.h:120:74: note: in expansion of macro ‘__alloc_size’
>>      [...]
>>
>> It's building fine with e.g. gcc-9 (which is my usual m68k cross-compiler).
>> Reverting this commit on next-20220927 fixes the issue.
>>
>> [1] http://kisskb.ellerman.id.au/kisskb/buildresult/14803908/
>> [2] http://kisskb.ellerman.id.au/kisskb/head/1bd8b75fe6adeaa89d02968bdd811ffe708cf839/
> 
> Eek! Thanks for letting me know. I'm confused about this --
> __alloc_size__ wasn't optional in compiler_attributes.h -- but obviously
> I broke something! I'll go figure this out.

Even in latest next I can see at the end of include/linux/compiler-gcc.h

/*
  * Prior to 9.1, -Wno-alloc-size-larger-than (and therefore the "alloc_size"
  * attribute) do not work, and must be disabled.
  */
#if GCC_VERSION < 90100
#undef __alloc_size__
#endif



> -Kees
> 


  reply	other threads:[~2022-09-28 21:40 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-23 20:28 [PATCH v2 00/16] slab: Introduce kmalloc_size_roundup() Kees Cook
2022-09-23 20:28 ` [PATCH v2 01/16] slab: Remove __malloc attribute from realloc functions Kees Cook
2022-09-28  7:26   ` Geert Uytterhoeven
2022-09-28 16:27     ` Vlastimil Babka
2022-09-28 17:13     ` Kees Cook
2022-09-28 21:39       ` Vlastimil Babka [this message]
2022-09-29  8:36       ` Michael Ellerman
2022-09-29  9:00         ` Geert Uytterhoeven
2022-10-01 16:09   ` Hyeonggon Yoo
2022-09-23 20:28 ` [PATCH v2 02/16] slab: Introduce kmalloc_size_roundup() Kees Cook
2022-09-26 13:15   ` Vlastimil Babka
2022-09-26 17:50     ` Kees Cook
2022-10-01 16:28   ` Hyeonggon Yoo
2022-09-23 20:28 ` [PATCH v2 03/16] skbuff: Proactively round up to kmalloc bucket size Kees Cook
2022-09-24  9:11   ` Kees Cook
2022-09-23 20:28 ` [PATCH v2 04/16] skbuff: Phase out ksize() fallback for frag_size Kees Cook
2022-09-25  7:17   ` Paolo Abeni
2022-09-26  0:41     ` Kees Cook
2022-09-23 20:28 ` [PATCH v2 05/16] net: ipa: Proactively round up to kmalloc bucket size Kees Cook
2022-09-23 20:28 ` [PATCH v2 06/16] igb: " Kees Cook
2022-09-26 15:49   ` Ruhl, Michael J
2022-09-23 20:28 ` [PATCH v2 07/16] btrfs: send: " Kees Cook
2022-09-23 20:28 ` [PATCH v2 08/16] dma-buf: " Kees Cook
2022-09-26  9:29   ` [Linaro-mm-sig] " Christian König
2022-09-23 20:28 ` [PATCH v2 09/16] coredump: " Kees Cook
2022-09-23 20:28 ` [PATCH v2 10/16] openvswitch: Use kmalloc_size_roundup() to match ksize() usage Kees Cook
2022-09-23 20:28 ` [PATCH v2 11/16] bpf: " Kees Cook
2022-09-23 20:28 ` [PATCH v2 12/16] devres: " Kees Cook
2022-09-23 20:28 ` [PATCH v2 13/16] mempool: " Kees Cook
2022-09-26 13:50   ` Vlastimil Babka
2022-09-26 18:24     ` Kees Cook
2022-09-23 20:28 ` [PATCH v2 14/16] kasan: Remove ksize()-related tests Kees Cook
2022-09-24  8:15   ` Dmitry Vyukov
2022-09-26  0:38     ` Kees Cook
2022-09-23 20:28 ` [PATCH v2 15/16] mm: Make ksize() a reporting-only function Kees Cook
2022-09-23 20:28 ` [PATCH v2 16/16] slab: Restore __alloc_size attribute to __kmalloc_track_caller Kees Cook

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