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:   Mon, 15 Aug 2022 15:27:43 +0800
From:   Feng Tang <feng.tang@intel.com>
To:     Dmitry Vyukov <dvyukov@google.com>,
        "Sang, Oliver" <oliver.sang@intel.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: <Yvn1b8y20Mr0gfUQ@feng-clx>
References: <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>
 <Yuu6B0vUuXvtEG8b@feng-clx>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <Yuu6B0vUuXvtEG8b@feng-clx>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?VFOBn4+PrKRqJLiqVU72sa8W1G6+Pvb70ly6Wn0NrNY0fZeOmA2QOJKHjW7n?=
 =?us-ascii?Q?1qN2cRNuAGapUvv/KMnQ7lJuRQaE6MjURwBl+pD7t0GfxTbTdjqbW3lvPY4O?=
 =?us-ascii?Q?E9w4J5OIXmuA4uZqJJvGu9+YVUdbCOsRTATPiFCefgsa4qwzHD2KxAHKzDE+?=
 =?us-ascii?Q?1h2/RpWl2MOXLVptRh2NwcKHsVovKnMIO1BuD0xY+Tkjj5eAN/WZ56lARLba?=
 =?us-ascii?Q?yTmjHmFEp2y+0mZ4DZjvJ/u2rzUp5dn/LO2Q+VIsQhm9FxfED9KzfplGJ5AS?=
 =?us-ascii?Q?XfMxIOjpTDlBbXTlS10T/+tOhp3OB7PLYdlPqjYe7lcsM9njBlrvy6IQNl5o?=
 =?us-ascii?Q?0orGXbBm0GhjmDcyqJ4+7uLS9YvzJj2eeX0pWjYVF3ndpHT+KNTCxe6pUCfM?=
 =?us-ascii?Q?DhJEnYBOQ6VVz0wPBIhk9p0W3lVrfJmim3eVfwr2rD8YCY04t9kdvfjY46oE?=
 =?us-ascii?Q?Z6wPSigMZ24n5Y+nyMfOXkNIR5EiFUiEFgujhOlc/0hB6hhZJ3sLRaVwT9O7?=
 =?us-ascii?Q?rk/hu66i13r6omS0puwzv57LqR/2ZuVfsm6GBpnS8JMBmC2CDLcqcbU5MMnP?=
 =?us-ascii?Q?PI4NKRGj9DldJS/sM32EzXtdtzH5o47Yyi0EI2iEu6DUBQTpo3my1/aR3Md7?=
 =?us-ascii?Q?AEFjMhFMzfn0sZVmYJuti5Dwyz2g3diBd6T7C4vpN/VWWXgRBgwWMuIgzUrw?=
 =?us-ascii?Q?dWDK6hDgNDrqnJwyJAqDdW+zJtoGqtvA83aLkBZ+EnHb+hQR6rbJTvv7RhvZ?=
 =?us-ascii?Q?qUJX9HN9GijosjN+E90AxGUzR2jSOnClgwMStv001z0vI2fV1qBOWUMkjMlW?=
 =?us-ascii?Q?tgf5/AhXrJeMRG0e8KREYt95jMHBig/pDM14sZAyqlSFERXvdg8MUQguRq2K?=
 =?us-ascii?Q?ejmync8ARcOW4rMZfrEa5ltzr96SX79bV9OeHBKU/lROlYO9njPLyN/R3oc6?=
 =?us-ascii?Q?nZ6bcnX7M/nFE7l2gS53yeQJbR120y23aP8ltAme4ZCkYYwupy6qFc4fvZUr?=
 =?us-ascii?Q?FQX/5OJMItI0rJnOb3wIDnsIzkjXoBvKapkDeqnRP2pxzxWZt5zzt8Sb4aO0?=
 =?us-ascii?Q?be0JsnPJZQo0+xib5Pj4yRgaPT3RHNlxYcQSFLKIQYPC8PaZW+sziPgxyMmM?=
 =?us-ascii?Q?imRu7lTRDgh32XrVmfHiT8wh+/k9lJfTdB6fVU2WT6MIwt2DGBs31NGcumUN?=
 =?us-ascii?Q?PBEU00VfyiWrP11WqHDtAs8dUDNlhpKuVBMw/bJURKHlPjBpbmKVzuPto511?=
 =?us-ascii?Q?mNMZTCS/SUMs7dh2p4brqrufLveC97AK2fYRIF/qPOgozWgyNIlEIbR26w0C?=
 =?us-ascii?Q?1w1sL2hmkka+Ix1i8Be+vbJLxJPYi1LtVYs0zhndwesiGSFMasIq9DuDqYHf?=
 =?us-ascii?Q?Zj+qJt8Iz+ONIN01WQi9iA5xSA4GCpp+4BP3HG4vCUP/L7dis2no+1mapJtB?=
 =?us-ascii?Q?LPL4n/3bcboLgLRApsKlzvR8u+ISdcGcx0mDpBMeU2woqGEh+zJD/MMO/rdR?=
 =?us-ascii?Q?mAklceddkAPfkWBPjp41FQdO3Su1R2Idlnw9pCFYNCojj4gfYzAAMjAjnAMZ?=
 =?us-ascii?Q?sNv/6smZlZHdmHMgoOm5Kb6rBL8YbjUVQtvb2b8z?=
X-MS-Exchange-CrossTenant-Network-Message-Id: eb14b16b-c25c-4ae9-eff4-08da7e8fc2f5
X-MS-Exchange-CrossTenant-AuthSource: MN0PR11MB6304.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Aug 2022 07:28:34.5166
 (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: 31kFIIYbtEZcsjCHbXJQD73TptLLDwguL8W5VKJAbfqX4lp+WXLbSFGkF5R/5pvm8oYhZI+Owtgd/KcnOCmQsQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR11MB4209
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-7.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI,
        RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,
        T_SCC_BODY_TEXT_LINE 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

Hi Oliver,

Could you help to check if the below combined patch fix the problem
you reported? thanks!

- Feng

---

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index b092277bf48d6..293bdaa0ba09c 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 c40c0e7b3b5f1..9d2994dbe4e7a 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -200,6 +200,8 @@ 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. */
diff --git a/mm/slub.c b/mm/slub.c
index added2653bb03..272dcdbaaa03b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -830,6 +830,16 @@ static inline void set_orig_size(struct kmem_cache *s,
 	if (!slub_debug_orig_size(s))
 		return;
 
+#ifdef CONFIG_KASAN_GENERIC
+	/*
+	 * kasn could save its free meta data in the start part of object
+	 * area, so skip the redzone check if kasan's meta data size is
+	 * bigger enough to possibly overlap with kmalloc redzone
+	 */
+	if (s->kasan_info.free_meta_size_in_object * 2 > s->object_size)
+		orig_size = s->object_size;
+#endif
+
 	p += get_info_end(s);
 	p += sizeof(struct track) * 2;
 
On Thu, Aug 04, 2022 at 08:22:31PM +0800, Tang, Feng wrote:
> 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
> >