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From: Kees Cook <keescook@chromium.org>
To: Guenter Roeck <linux@roeck-us.net>
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 14:11:15 -0800	[thread overview]
Message-ID: <202202021409.2AA6A4246@keescook> (raw)
In-Reply-To: <20220202160903.GA2337834@roeck-us.net>

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

-- 
Kees Cook

  parent reply	other threads:[~2022-02-02 22:12 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 [this message]
2022-02-02 23:21       ` Guenter Roeck
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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