Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 4 Aug 2022 20:22:31 +0800
From:   Feng Tang <feng.tang@intel.com>
To:     Dmitry Vyukov <dvyukov@google.com>
CC:     Vlastimil Babka <vbabka@suse.cz>,
        "Sang, Oliver" <oliver.sang@intel.com>, lkp <lkp@intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "lkp@lists.01.org" <lkp@lists.01.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Christoph Lameter" <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        "Hansen, Dave" <dave.hansen@intel.com>,
        Robin Murphy <robin.murphy@arm.com>,
        "John Garry" <john.garry@huawei.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        "kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>
Subject: Re: [mm/slub] 3616799128:
 BUG_kmalloc-#(Not_tainted):kmalloc_Redzone_overwritten
Message-ID: <Yuu6B0vUuXvtEG8b@feng-clx>
References: <Yudw5ge/lJ26Hksk@feng-skl>
 <0e545088-d140-4c84-bbb2-a3be669740b2@suse.cz>
 <YujKCxu2lJJFm73P@feng-skl>
 <CACT4Y+Zwg8BP=6WJpQ5cCbJxLu4HcnCjx8e53aDEbTZ5uzpUyg@mail.gmail.com>
 <85ec4ea8-ae4c-3592-5491-3db6d0ad8c59@suse.cz>
 <CACT4Y+asjzrBu8ogRDt9hYYaAB3tZ2pK5HBkzkuMp106vQwKWQ@mail.gmail.com>
 <YukoZEm4Q6CSEKKj@feng-skl>
 <CACT4Y+Y6M5MqSGC0MERFqkxgKYK+LrMYvW5xPH5kUA2mFh5_Xw@mail.gmail.com>
 <YutnCD5dPie/yoIk@feng-clx>
 <CACT4Y+Zzzj7+LwUwyMoBketXFBHRksnx148B1aLATZ48AU9o3w@mail.gmail.com>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <CACT4Y+Zzzj7+LwUwyMoBketXFBHRksnx148B1aLATZ48AU9o3w@mail.gmail.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?yv2sXUp5tC9H8TZtP1gvDIG+CdU3Eb3mAWa/LBF2S9GgvFw0E74fTDQBskwM?=
 =?us-ascii?Q?qxZAc1XXt5wAojMzRyo79X/+VLEEPrkZON+SSCMFgWHWTseG8tU3y2zFytRM?=
 =?us-ascii?Q?/ofeUZ8MdRzA6IDl/UeUbZIh+b74CM33XIJvaHNz+fjvcgb/E1/NLdq3aDFf?=
 =?us-ascii?Q?D6SY7oSpWFGPSYz/YHyKq57sgiuOcc0LBxOv637Xxk+rIYCjEb9yegG45K19?=
 =?us-ascii?Q?/g0iO4FaaqW9GOnK2Rp4PfEFYS+SHHnkitBAjHT0vJzIIKbrnVS8umCsKzir?=
 =?us-ascii?Q?cL6fsy0UuJqGhsnVZ3v35Y4bab8quzcf5CJXONxGUfdHdXp7ttmjCxa1/xIu?=
 =?us-ascii?Q?zN53phQVjHZPg0ZeuRenuFzZeYn0ljNKpybfEXJZ/aDN44+0RMrD3ZL92sv6?=
 =?us-ascii?Q?zB8BWVAdO0KA6kT+eomv+usZ0bwKnSvVx3dqNt0csEPJKmVpC6+R836HvDl8?=
 =?us-ascii?Q?l5jTw0XoFed1Bz6ia1CVYdVmrhGTNyI/yrkBx1a+KE+ebvMXjlmI+1F8fxKo?=
 =?us-ascii?Q?9t2crs+xl2tgCGKL2mx7ZxFS+MZCV1phPO/eOtHgFgVKzx9VkZukHUpwT4X9?=
 =?us-ascii?Q?/cm46nf4bfwiNIjeoOhVE4Hn9WKRTOCzUWtv4LNmyv3wvZwz7etynhqDFbN/?=
 =?us-ascii?Q?eH0qU/Btpgqgqp8GXs3Cfhe7mw18WbJI+vDLABGGLl73bhoM+30VFfO5+c50?=
 =?us-ascii?Q?1EhGVl1JRAcmXSnpqPQd4gwF2zscraHsM57uQ5ZRVG1I2QUv+j4kKqH2Bpoi?=
 =?us-ascii?Q?NHsQpoVIV9TzIKprbVksRBz0VDvreuJA3jt29fgU5P8FHw0pdq+iFRpjM1pG?=
 =?us-ascii?Q?GHng1EhiRVjxCD5fNXAaMfBIOuuSoAzd+Jh7fJgx3iCvbPZLMTKrZqKVCtXj?=
 =?us-ascii?Q?oGcmJtIXP0/TZtS3ht1/r6DqzC1qEvlTGCHtrZcJy26qjYXXUG1bIwK6bq5Z?=
 =?us-ascii?Q?PUUFeR2gEKfGul5oSZDWvggfqrRcnaj6zPPaesLZYkjccWA7avStDVjJ+yZB?=
 =?us-ascii?Q?vnDjL184G5j54bw6Xqo1MXGx3CitPMXIvbRan1OUZ7KEqwrDOn1LaMiSxfPN?=
 =?us-ascii?Q?emVpZ9SAoFwyiAAi6eqjLgAQY3oky47F86R2xXeyYpim38caONvt/xxj8CGj?=
 =?us-ascii?Q?3+O4zFL/fTFZNs9tDUdlfrdSiChQyGd4+kvaSLiX2HEJgYgakAAs61RQgD7k?=
 =?us-ascii?Q?Hj5jPhxxc/NFBQ/2U5/Om0us+AkwwK4Ua3gz3ngo1skmKEM9ZpE5JZl1AcUL?=
 =?us-ascii?Q?FS6NLIP1a58OqSPKF7n35VOxOcSG84RRRvUB9CXuN/W93DF1n+B5IksvmehN?=
 =?us-ascii?Q?lC6y5lLbh8zBh3IRzxp3QUZJy56GVXLuNAWe6av+zsCeV3CMIzeSu28yh4YO?=
 =?us-ascii?Q?usiDUJaGSZJTAlda+Zci7VxKm3V9Po2YuZwD3EW5f5UQXL/AJqULgqYY+ALL?=
 =?us-ascii?Q?eafuoXdsL0CInvWVNs5dB+sbucdiiKXXdCxmF2aCGv1Rp9ej2zmyaUMprKi4?=
 =?us-ascii?Q?ZUbn7P5aBBEug3cNWFRQM1sfZvmf2r5NkEXVT02iHwo0qCEy6U1Yji92dh/c?=
 =?us-ascii?Q?td1Tyr+CZ2cHhJXfu0x1VQO3ObwGAd3qJ6EMYkCQ?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 16a4faa3-41a5-4e1c-77c5-08da76141ff0
X-MS-Exchange-CrossTenant-AuthSource: MN0PR11MB6304.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Aug 2022 12:23:23.5810
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: cXpi1Rqb39/saqNQeFDkN56gvvFtVHJNCqpgthmn+qvx+MUz+aktcVXKpx3qjnFdwSaLRUpXII5Mbf0mwZwiNQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR11MB6042
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-5.0 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,
        SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Aug 04, 2022 at 06:47:58PM +0800, Dmitry Vyukov wrote:
>  On Thu, 4 Aug 2022 at 08:29, Feng Tang <feng.tang@intel.com> wrote:
[...]
> >
> > ---8<---
> > From c4fc739ea4d5222f0aba4b42b59668d64a010082 Mon Sep 17 00:00:00 2001
> > From: Feng Tang <feng.tang@intel.com>
> > Date: Thu, 4 Aug 2022 13:25:35 +0800
> > Subject: [PATCH] mm: kasan: Add free_meta size info in struct kasan_cache
> >
> > When kasan is enabled for slab/slub, it may save kasan' free_meta
> > data in the former part of slab object data area in slab object
> > free path, which works fine.
> >
> > There is ongoing effort to extend slub's debug function which will
> > redzone the latter part of kmalloc object area, and when both of
> > the debug are enabled, there is possible conflict, especially when
> > the kmalloc object has small size, as caught by 0Day bot [1]
> >
> > For better information for slab/slub, add free_meta's data size
> > info 'kasan_cache', so that its users can take right action to
> > avoid data conflict.
> >
> > [1]. https://lore.kernel.org/lkml/YuYm3dWwpZwH58Hu@xsang-OptiPlex-9020/
> > Reported-by: kernel test robot <oliver.sang@intel.com>
> > Signed-off-by: Feng Tang <feng.tang@intel.com>
> 
> Acked-by: Dmitry Vyukov <dvyukov@google.com>
 
Thanks for your suggestion and review!

> I assume there will be a second patch that uses
> free_meta_size_in_object  in slub debug code.
 
Yes, it will be called in the slub kmalloc object redzone debug code.

Thanks,
Feng

> > ---
> >  include/linux/kasan.h | 2 ++
> >  mm/kasan/common.c     | 2 ++
> >  2 files changed, 4 insertions(+)
> >
> > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> > index b092277bf48d..293bdaa0ba09 100644
> > --- a/include/linux/kasan.h
> > +++ b/include/linux/kasan.h
> > @@ -100,6 +100,8 @@ static inline bool kasan_has_integrated_init(void)
> >  struct kasan_cache {
> >         int alloc_meta_offset;
> >         int free_meta_offset;
> > +       /* size of free_meta data saved in object's data area */
> > +       int free_meta_size_in_object;
> >         bool is_kmalloc;
> >  };
> >
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index 78be2beb7453..a627efa267d1 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -201,6 +201,8 @@ void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
> >                         cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
> >                         *size = ok_size;
> >                 }
> > +       } else {
> > +               cache->kasan_info.free_meta_size_in_object = sizeof(struct kasan_free_meta);
> >         }
> >
> >         /* Calculate size with optimal redzone. */
> > --
> > 2.27.0
>