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From: Guenter Roeck <linux@roeck-us.net>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Masahiro Yamada <masahiroy@kernel.org>,
	linux-kbuild@vger.kernel.org,
	"Gustavo A . R . Silva" <gustavoars@kernel.org>,
	clang-built-linux@googlegroups.com,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH 4/5] Makefile: Enable -Warray-bounds
Date: Wed, 2 Feb 2022 15:21:49 -0800	[thread overview]
Message-ID: <5ce016f8-fb4b-ef50-c543-886b4cfda225@roeck-us.net> (raw)
In-Reply-To: <202202021409.2AA6A4246@keescook>

On 2/2/22 14:11, Kees Cook wrote:
> On Wed, Feb 02, 2022 at 08:09:03AM -0800, Guenter Roeck wrote:
>> On Wed, Aug 18, 2021 at 01:11:17AM -0700, Kees Cook wrote:
>>> With the recent fixes for flexible arrays and expanded FORTIFY_SOURCE
>>> coverage, it is now possible to enable -Warray-bounds. Since both
>>> GCC and Clang include -Warray-bounds in -Wall, we just need to stop
>>> disabling it.
>>>
>>> Cc: Arnd Bergmann <arnd@arndb.de>
>>> Cc: Masahiro Yamada <masahiroy@kernel.org>
>>> Cc: linux-kbuild@vger.kernel.org
>>> Co-developed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>> ---
>>>   Makefile | 1 -
>>>   1 file changed, 1 deletion(-)
>>>
>>> diff --git a/Makefile b/Makefile
>>> index a4aca01a4835..af22b83cede7 100644
>>> --- a/Makefile
>>> +++ b/Makefile
>>> @@ -1072,7 +1072,6 @@ KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
>>>   
>>>   # We'll want to enable this eventually, but it's not going away for 5.7 at least
>>>   KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds)
>>> -KBUILD_CFLAGS += -Wno-array-bounds
>>>   KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
>>>   
>>>   # Another good warning that we'll want to enable eventually
>>
>> alpha:defconfig:
>>
>> In function '__memset',
>>      inlined from '__bad_pagetable' at arch/alpha/mm/init.c:79:2:
>> ./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds]
>>     37 |                         return __builtin_memset(s, c, n);
>>        |                                ^~~~~~~~~~~~~~~~~~~~~~~~~
>> In function '__memset',
>>      inlined from '__bad_page' at arch/alpha/mm/init.c:86:2:
>> ./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds]
>>     37 |                         return __builtin_memset(s, c, n);
>>        |                                ^~~~~~~~~~~~~~~~~~~~~~~~~
>> In function '__memset',
>>      inlined from 'paging_init' at arch/alpha/mm/init.c:256:2:
>> ./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds]
>>     37 |                         return __builtin_memset(s, c, n);
> 
> Ah! With Arnd and Nathan's help, I saw:
> https://lore.kernel.org/all/20210912160149.2227137-3-linux@roeck-us.net/

Guilty as charged. Sorry, I didn't try to analyze the problem,
or I might have noticed (and saved you some work).

Guenter

> which is solving the same problem (just manifested through different
> diagnostics). The same solution works here. I'll get the patches sent...
> 


  reply	other threads:[~2022-02-02 23:21 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18  8:11 [PATCH 0/5] Enable -Warray-bounds and -Wzero-length-bounds Kees Cook
2021-08-18  8:11 ` [PATCH 1/5] stddef: Add flexible array union helper Kees Cook
2021-08-18  8:11 ` [PATCH 2/5] treewide: Replace open-coded flex arrays in unions Kees Cook
2021-08-18  9:56   ` Marc Kleine-Budde
2021-08-18 21:51     ` Kees Cook
2021-08-18  8:11 ` [PATCH 3/5] treewide: Replace 0-element memcpy() destinations with flexible arrays Kees Cook
2021-08-18  8:11 ` [PATCH 4/5] Makefile: Enable -Warray-bounds Kees Cook
2022-02-02 16:09   ` Guenter Roeck
2022-02-02 20:56     ` Kees Cook
2022-02-02 23:33       ` Guenter Roeck
2022-02-03  3:03         ` Kees Cook
2022-02-02 22:02     ` Kees Cook
2022-02-02 22:11     ` Kees Cook
2022-02-02 23:21       ` Guenter Roeck [this message]
2022-02-03  3:02         ` Kees Cook
2021-08-18  8:11 ` [PATCH 5/5] Makefile: Enable -Wzero-length-bounds Kees Cook
2021-08-25 21:17   ` Nick Desaulniers

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