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From: Nick Desaulniers <ndesaulniers@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Daniel Micay <danielmicay@gmail.com>,
	Francis Laniel <laniel_francis@privacyrequired.com>,
	Bart Van Assche <bvanassche@acm.org>,
	David Gow <davidgow@google.com>,
	linux-mm@kvack.org, clang-built-linux@googlegroups.com,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH for-next 16/25] fortify: Explicitly disable Clang support
Date: Wed, 25 Aug 2021 12:41:56 -0700	[thread overview]
Message-ID: <CAKwvOd=A+ueGV2ihdy5GtgR2fQbcXjjAtVxv3=cPjffpebZB7A@mail.gmail.com> (raw)
In-Reply-To: <20210822075122.864511-17-keescook@chromium.org>

On Sun, Aug 22, 2021 at 12:57 AM Kees Cook <keescook@chromium.org> wrote:
>
> Clang has never correctly compiled the FORTIFY_SOURCE defenses due to
> a couple bugs:
>
>         Eliding inlines with matching __builtin_* names
>         https://bugs.llvm.org/show_bug.cgi?id=50322
>
>         Incorrect __builtin_constant_p() of some globals
>         https://bugs.llvm.org/show_bug.cgi?id=41459
>
> In the process of making improvements to the FORTIFY_SOURCE defenses, the
> first (silent) bug (coincidentally) becomes worked around, but exposes
> the latter which breaks the build. As such, Clang must not be used with
> CONFIG_FORTIFY_SOURCE until at least latter bug is fixed (in Clang 13),
> and the fortify routines have been rearranged.
>
> Update the Kconfig to reflect the reality of the current situation.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>

Acked-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>  security/Kconfig | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/security/Kconfig b/security/Kconfig
> index 0ced7fd33e4d..fe6c0395fa02 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -191,6 +191,9 @@ config HARDENED_USERCOPY_PAGESPAN
>  config FORTIFY_SOURCE
>         bool "Harden common str/mem functions against buffer overflows"
>         depends on ARCH_HAS_FORTIFY_SOURCE
> +       # https://bugs.llvm.org/show_bug.cgi?id=50322
> +       # https://bugs.llvm.org/show_bug.cgi?id=41459
> +       depends on !CC_IS_CLANG
>         help
>           Detect overflows of buffers in common string and memory functions
>           where the compiler can determine and validate the buffer sizes.
> --
> 2.30.2
>
> --
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> To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210822075122.864511-17-keescook%40chromium.org.



-- 
Thanks,
~Nick Desaulniers

  reply	other threads:[~2021-08-25 19:42 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-22  7:50 [PATCH for-next 00/25] Prepare for better FORTIFY_SOURCE Kees Cook
2021-08-22  7:50 ` [PATCH for-next 01/25] scsi: ibmvscsi: Avoid multi-field memset() overflow by aiming at srp Kees Cook
2021-08-22  7:50 ` [PATCH for-next 02/25] powerpc: Split memset() to avoid multi-field overflow Kees Cook
2021-08-22  7:51 ` [PATCH for-next 03/25] stddef: Fix kerndoc for sizeof_field() and offsetofend() Kees Cook
2021-08-22  7:51 ` [PATCH for-next 04/25] stddef: Introduce struct_group() helper macro Kees Cook
2021-08-22  7:51 ` [PATCH for-next 05/25] cxl/core: Replace unions with struct_group() Kees Cook
2021-08-22  7:51 ` [PATCH for-next 06/25] bnxt_en: Use struct_group_attr() for memcpy() region Kees Cook
2021-08-22  7:51 ` [PATCH for-next 07/25] iommu/amd: Use struct_group() " Kees Cook
2021-08-22  7:51 ` [PATCH for-next 08/25] drm/mga/mga_ioc32: " Kees Cook
2021-08-22  7:51 ` [PATCH for-next 09/25] HID: cp2112: " Kees Cook
2021-08-22  7:51 ` [PATCH for-next 10/25] HID: roccat: Use struct_group() to zero kone_mouse_event Kees Cook
2021-08-22  7:51 ` [PATCH for-next 11/25] can: flexcan: Use struct_group() to zero struct flexcan_regs regions Kees Cook
2021-08-22  7:51 ` [PATCH for-next 12/25] cm4000_cs: Use struct_group() to zero struct cm4000_dev region Kees Cook
2021-08-22  7:51 ` [PATCH for-next 13/25] compiler_types.h: Remove __compiletime_object_size() Kees Cook
2021-08-23  6:43   ` Rasmus Villemoes
2021-08-25 19:43     ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 14/25] lib/string: Move helper functions out of string.c Kees Cook
2021-08-25 21:48   ` Nick Desaulniers
2021-08-26  2:47     ` Kees Cook
2021-08-26 18:08       ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 15/25] fortify: Move remaining fortify helpers into fortify-string.h Kees Cook
2021-08-25 21:59   ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 16/25] fortify: Explicitly disable Clang support Kees Cook
2021-08-25 19:41   ` Nick Desaulniers [this message]
2021-08-22  7:51 ` [PATCH for-next 17/25] fortify: Fix dropped strcpy() compile-time write overflow check Kees Cook
2021-08-25 21:55   ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 18/25] fortify: Prepare to improve strnlen() and strlen() warnings Kees Cook
2021-08-25 22:01   ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 19/25] fortify: Allow strlen() and strnlen() to pass compile-time known lengths Kees Cook
2021-08-25 22:05   ` Nick Desaulniers
2021-08-26  2:56     ` Kees Cook
2021-08-26 18:02       ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 20/25] fortify: Add compile-time FORTIFY_SOURCE tests Kees Cook
2021-08-22  7:51 ` [PATCH for-next 21/25] lib: Introduce CONFIG_TEST_MEMCPY Kees Cook
2021-08-24  7:00   ` David Gow
2021-08-25  2:32     ` Kees Cook
2021-10-18 15:46   ` Arnd Bergmann
2021-10-18 19:28     ` Kees Cook
2021-08-22  7:51 ` [PATCH for-next 22/25] string.h: Introduce memset_after() for wiping trailing members/padding Kees Cook
2021-08-22  7:51 ` [PATCH for-next 23/25] xfrm: Use memset_after() to clear padding Kees Cook
2021-08-22  7:51 ` [PATCH for-next 24/25] string.h: Introduce memset_startat() for wiping trailing members and padding Kees Cook
2021-08-22  7:51 ` [PATCH for-next 25/25] btrfs: Use memset_startat() to clear end of struct Kees Cook

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