linux-kernel - Re: [PATCH] mm: prevent KASAN false positives in kmemleak

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Message-ID: <20160623095951.GH6521@e104818-lin.cambridge.arm.com>
Date:	Thu, 23 Jun 2016 10:59:51 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	linux-mm@...ck.org, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, ryabinin.a.a@...il.com,
	kasan-dev@...glegroups.com, glider@...gle.com
Subject: Re: [PATCH] mm: prevent KASAN false positives in kmemleak

On Wed, Jun 22, 2016 at 07:47:11PM +0200, Dmitry Vyukov wrote:
> When kmemleak dumps contents of leaked objects it reads whole
> objects regardless of user-requested size. This upsets KASAN.
> Disable KASAN checks around object dump.
> 
> Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
> ---
>  mm/kmemleak.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index e642992..04320d3 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -307,8 +307,10 @@ static void hex_dump_object(struct seq_file *seq,
>  	len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
>  
>  	seq_printf(seq, "  hex dump (first %zu bytes):\n", len);
> +	kasan_disable_current();
>  	seq_hex_dump(seq, "    ", DUMP_PREFIX_NONE, HEX_ROW_SIZE,
>  		     HEX_GROUP_SIZE, ptr, len, HEX_ASCII);
> +	kasan_enable_current();
>  }

Acked-by: Catalin Marinas <catalin.marinas@....com>