linux-kernel - Re: [PATCH v3 1/3] kasan: Archs don't check memmove if not support it.

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Message-ID: <ba456776-a77f-5306-60ef-c19a4a8b3119@virtuozzo.com>
Date:   Thu, 17 Oct 2019 13:39:12 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Nick Hu <nickhu@...estech.com>, alankao@...estech.com,
        paul.walmsley@...ive.com, palmer@...ive.com, aou@...s.berkeley.edu,
        glider@...gle.com, dvyukov@...gle.com, corbet@....net,
        alexios.zavras@...el.com, allison@...utok.net, Anup.Patel@....com,
        tglx@...utronix.de, gregkh@...uxfoundation.org,
        atish.patra@....com, kstewart@...uxfoundation.org,
        linux-doc@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        linux-mm@...ck.org
Subject: Re: [PATCH v3 1/3] kasan: Archs don't check memmove if not support
 it.



On 10/8/19 9:11 AM, Nick Hu wrote:
> Skip the memmove checking for those archs who don't support it.
 
The patch is fine but the changelog sounds misleading. We don't skip memmove checking.
If arch don't have memmove than the C implementation from lib/string.c used.
It's instrumented by compiler so it's checked and we simply don't need that KASAN's memmove with
manual checks.

> Signed-off-by: Nick Hu <nickhu@...estech.com>
> ---
>  mm/kasan/common.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 6814d6d6a023..897f9520bab3 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -107,6 +107,7 @@ void *memset(void *addr, int c, size_t len)
>  	return __memset(addr, c, len);
>  }
>  
> +#ifdef __HAVE_ARCH_MEMMOVE
>  #undef memmove
>  void *memmove(void *dest, const void *src, size_t len)
>  {
> @@ -115,6 +116,7 @@ void *memmove(void *dest, const void *src, size_t len)
>  
>  	return __memmove(dest, src, len);
>  }
> +#endif
>  
>  #undef memcpy
>  void *memcpy(void *dest, const void *src, size_t len)
>