Subject: Re: [PATCH v2 1/2] mm, kasan: don't call kasan_krealloc() from
 ksize().
To: Alexander Potapenko <glider@google.com>, <adech.fo@gmail.com>,
        <dvyukov@google.com>, <cl@linux.com>, <akpm@linux-foundation.org>,
        <kcc@google.com>
References: <2126fe9ca8c3a4698c0ad7aae652dce28e261182.1460545373.git.glider@google.com>
CC: <kasan-dev@googlegroups.com>, <linux-kernel@vger.kernel.org>,
        <linux-mm@kvack.org>
From: Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <57110FAF.8070401@virtuozzo.com>
Date: Fri, 15 Apr 2016 18:58:39 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.7.0
MIME-Version: 1.0
In-Reply-To: <2126fe9ca8c3a4698c0ad7aae652dce28e261182.1460545373.git.glider@google.com>
Content-Type: text/plain; charset="windows-1252"
Content-Transfer-Encoding: 7bit
SpamDiagnosticOutput: 1:23
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Apr 2016 15:58:19.5327 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM5PR0801MB1298
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1353
Lines: 47


On 04/13/2016 02:20 PM, Alexander Potapenko wrote:
> Instead of calling kasan_krealloc(), which replaces the memory allocation
> stack ID (if stack depot is used), just unpoison the whole memory chunk.
> 
> Signed-off-by: Alexander Potapenko <glider@google.com>

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

> ---
> v2: - splitted v1 into two patches
> ---
>  mm/slab.c | 2 +-
>  mm/slub.c | 5 +++--
>  2 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/slab.c b/mm/slab.c
> index 17e2848..de46319 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -4324,7 +4324,7 @@ size_t ksize(const void *objp)
>  	/* We assume that ksize callers could use the whole allocated area,
>  	 * so we need to unpoison this area.
>  	 */
> -	kasan_krealloc(objp, size, GFP_NOWAIT);
> +	kasan_unpoison_shadow(objp, size);
>  
>  	return size;
>  }
> diff --git a/mm/slub.c b/mm/slub.c
> index 4dbb109e..62194e2 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -3635,8 +3635,9 @@ size_t ksize(const void *object)
>  {
>  	size_t size = __ksize(object);
>  	/* We assume that ksize callers could use whole allocated area,
> -	   so we need unpoison this area. */
> -	kasan_krealloc(object, size, GFP_NOWAIT);
> +	 * so we need to unpoison this area.
> +	 */
> +	kasan_unpoison_shadow(object, size);
>  	return size;
>  }
>  EXPORT_SYMBOL(ksize);
>