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Subject: Re: [PATCH] kasan: add no_sanitize attribute for clang builds
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Rientjes <rientjes@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        David Woodhouse <dwmw@amazon.co.uk>,
        Will Deacon <will.deacon@arm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Paul Lawrence <paullawrence@google.com>,
        Sandipan Das <sandipan@linux.vnet.ibm.com>,
        Kees Cook <keescook@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Kostya Serebryany <kcc@google.com>
References: <4ad725cc903f8534f8c8a60f0daade5e3d674f8d.1523554166.git.andreyknvl@google.com>
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 <CAAeHK+y18zU_PAS5KB82PNqtvGNex+S0Jk3bWaE19=YjThaNow@mail.gmail.com>
From:   Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <c95bd92f-bef4-378a-55ed-04439c784e43@virtuozzo.com>
Date:   Fri, 13 Apr 2018 22:16:30 +0300
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On 04/13/2018 08:34 PM, Andrey Konovalov wrote:
> On Fri, Apr 13, 2018 at 5:31 PM, Andrey Ryabinin
> <aryabinin@virtuozzo.com> wrote:
>>
>>
>> On 04/12/2018 08:29 PM, Andrey Konovalov wrote:
>>> KASAN uses the __no_sanitize_address macro to disable instrumentation
>>> of particular functions. Right now it's defined only for GCC build,
>>> which causes false positives when clang is used.
>>>
>>> This patch adds a definition for clang.
>>>
>>> Note, that clang's revision 329612 or higher is required.
>>>
>>> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
>>> ---
>>>  include/linux/compiler-clang.h | 5 +++++
>>>  1 file changed, 5 insertions(+)
>>>
>>> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
>>> index ceb96ecab96e..5a1d8580febe 100644
>>> --- a/include/linux/compiler-clang.h
>>> +++ b/include/linux/compiler-clang.h
>>> @@ -25,6 +25,11 @@
>>>  #define __SANITIZE_ADDRESS__
>>>  #endif
>>>
>>> +#ifdef CONFIG_KASAN
>>
>> If, for whatever reason, developer decides to add __no_sanitize_address to some
>> generic function, guess what will happen next when he/she will try to build CONFIG_KASAN=n kernel?
> 
> It's defined to nothing in compiler-gcc.h and redefined in
> compiler-clang.h only if CONFIG_KASAN is enabled, so everything should
> be fine. Am I missing something?

No, It's was me missing something ;)
However, "#ifdef CONFIG_KASAN" seems to be redundant, I'd rather remove it.

Anyway:
	Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>