linux-kernel - Re: [PATCH v2 5/5] kasan: add compiler support for clang

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Date:   Thu, 30 Nov 2017 19:45:10 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Paul Lawrence <paullawrence@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <mmarek@...e.com>
Cc:     linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, linux-kbuild@...r.kernel.org,
        Matthias Kaehlcke <mka@...omium.org>,
        Michael Davidson <md@...gle.com>,
        Greg Hackmann <ghackmann@...gle.com>
Subject: Re: [PATCH v2 5/5] kasan: add compiler support for clang



On 11/30/2017 12:50 AM, Paul Lawrence wrote:
> For now we can hard-code ASAN ABI level 5, since historical clang builds
> can't build the kernel anyway.  We also need to emulate gcc's
> __SANITIZE_ADDRESS__ flag, or memset() calls won't be instrumented.
> 
> Signed-off-by: Greg Hackmann <ghackmann@...gle.com>
> Signed-off-by: Paul Lawrence <paullawrence@...gle.com>
> 
> ---
>  include/linux/compiler-clang.h | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> index 3b609edffa8f..d02a4df3f473 100644
> --- a/include/linux/compiler-clang.h
> +++ b/include/linux/compiler-clang.h
> @@ -19,3 +19,11 @@
>  
>  #define randomized_struct_fields_start	struct {
>  #define randomized_struct_fields_end	};
> +
> +/* all clang versions usable with the kernel support KASAN ABI version 5 */
> +#define KASAN_ABI_VERSION 5
> +

This patch should be earlier in this series. Patch 4/5 breaks clang-built kernel, because
we start using globals instrumentation with wrong KASAN_ABI_VERSION.

> +/* emulate gcc's __SANITIZE_ADDRESS__ flag */
> +#if __has_feature(address_sanitizer)
> +#define __SANITIZE_ADDRESS__
> +#endif
>