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Wed, 19 Jun 2019 21:07:52 +0000 Received: from DM6PR15MB2635.namprd15.prod.outlook.com ([fe80::5022:93e0:dd8b:b1a1]) by DM6PR15MB2635.namprd15.prod.outlook.com ([fe80::5022:93e0:dd8b:b1a1%7]) with mapi id 15.20.1987.014; Wed, 19 Jun 2019 21:07:52 +0000 From: Roman Gushchin To: Qian Cai CC: "akpm@linux-foundation.org" , "vdavydov.dev@gmail.com" , "hannes@cmpxchg.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH -next] mm/slab: fix an use-after-free in kmemcg_workfn() Thread-Topic: [PATCH -next] mm/slab: fix an use-after-free in kmemcg_workfn() Thread-Index: AQHVJuEXcoe79odJmU2xiisbFM7VSqajeFSA Date: Wed, 19 Jun 2019 21:07:52 +0000 Message-ID: <20190619210744.GA20256@castle.dhcp.thefacebook.com> References: <1560977573-10715-1-git-send-email-cai@lca.pw> In-Reply-To: <1560977573-10715-1-git-send-email-cai@lca.pw> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: MW2PR16CA0035.namprd16.prod.outlook.com (2603:10b6:907::48) To DM6PR15MB2635.namprd15.prod.outlook.com (2603:10b6:5:1a6::24) x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [2620:10d:c090:180::1:3e17] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: bea38161-70e6-45d9-8839-08d6f4fa30f0 x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600148)(711020)(4605104)(1401327)(2017052603328)(7193020);SRVR:DM6PR15MB3354; 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charset="us-ascii" Content-ID: <3BF7D0D93AD04C438A4924F834A5FD4B@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: bea38161-70e6-45d9-8839-08d6f4fa30f0 X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Jun 2019 21:07:52.2353 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: guro@fb.com X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR15MB3354 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-19_13:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906190173 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 19, 2019 at 04:52:53PM -0400, Qian Cai wrote: > The linux-next commit "mm: rework non-root kmem_cache lifecycle > management" [1] introduced an use-after-free below because > kmemcg_workfn() may call slab_kmem_cache_release() which has already > freed the whole kmem_cache. Fix it by removing the bogus NULL assignment > and checkings that will not work with SLUB_DEBUG poisoning anyway. >=20 > [1] https://lore.kernel.org/patchwork/patch/1087376/ >=20 > BUG kmem_cache (Tainted: G B W ): Poison overwritten > INFO: 0x(____ptrval____)-0x(____ptrval____). First byte 0x0 instead of > 0x6b > INFO: Allocated in create_cache+0x6c/0x1bc age=3D2653 cpu=3D154 pid=3D159= 9 > kmem_cache_alloc+0x514/0x568 > create_cache+0x6c/0x1bc > memcg_create_kmem_cache+0xfc/0x11c > memcg_kmem_cache_create_func+0x40/0x170 > process_one_work+0x4e0/0xa54 > worker_thread+0x498/0x650 > kthread+0x1b8/0x1d4 > ret_from_fork+0x10/0x18 > INFO: Freed in slab_kmem_cache_release+0x3c/0x48 age=3D255 cpu=3D7 pid=3D= 1505 > slab_kmem_cache_release+0x3c/0x48 > kmem_cache_release+0x1c/0x28 > kobject_cleanup+0x134/0x288 > kobject_put+0x5c/0x68 > sysfs_slab_release+0x2c/0x38 > shutdown_cache+0x190/0x234 > kmemcg_cache_shutdown_fn+0x1c/0x34 > kmemcg_workfn+0x44/0x68 > process_one_work+0x4e0/0xa54 > worker_thread+0x498/0x650 > kthread+0x1b8/0x1d4 > ret_from_fork+0x10/0x18 > INFO: Slab 0x(____ptrval____) objects=3D64 used=3D64 fp=3D0x(____ptrval__= __) > flags=3D0x17ffffffc000200 > INFO: Object 0x(____ptrval____) @offset=3D11601272640106456192 > fp=3D0x(____ptrval____) > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > bb ................ > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > bb ................ > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > bb ................ > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > bb ................ > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > bb ................ > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > bb ................ > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > bb ................ > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > bb ................ > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 00 00 00 00 > kkkkkkkk........ > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > kkkkkkkkkkkkkkkk > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b a5 > kkkkkkk. > Redzone (____ptrval____): bb bb bb bb bb bb bb bb > ........ > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > 5a ZZZZZZZZZZZZZZZZ > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > 5a ZZZZZZZZZZZZZZZZ > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > 5a ZZZZZZZZZZZZZZZZ > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > 5a ZZZZZZZZZZZZZZZZ > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a > ZZZZZZZZ > CPU: 193 PID: 1557 Comm: kworker/193:1 Tainted: G B W > 5.2.0-rc5-next-20190619+ #8 > Hardware name: HPE Apollo 70 /C01_APACHE_MB , BIOS > L50_5.13_1.0.9 03/01/2019 > Workqueue: memcg_kmem_cache memcg_kmem_cache_create_func > Call trace: > dump_backtrace+0x0/0x268 > show_stack+0x20/0x2c > dump_stack+0xb4/0x108 > print_trailer+0x274/0x298 > check_bytes_and_report+0xc4/0x118 > check_object+0x2fc/0x36c > alloc_debug_processing+0x154/0x240 > ___slab_alloc+0x710/0xa68 > kmem_cache_alloc+0x514/0x568 > create_cache+0x6c/0x1bc > memcg_create_kmem_cache+0xfc/0x11c > memcg_kmem_cache_create_func+0x40/0x170 > process_one_work+0x4e0/0xa54 > worker_thread+0x498/0x650 > kthread+0x1b8/0x1d4 > ret_from_fork+0x10/0x18 > FIX kmem_cache: Restoring 0x(____ptrval____)-0x(____ptrval____)=3D0x6b >=20 > FIX kmem_cache: Marking all objects used >=20 > Signed-off-by: Qian Cai > --- > mm/slab_common.c | 5 ----- > 1 file changed, 5 deletions(-) >=20 > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 91e8c739dc97..bb8aec6d8744 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -714,10 +714,7 @@ static void kmemcg_workfn(struct work_struct *work) > get_online_mems(); > =20 > mutex_lock(&slab_mutex); > - > s->memcg_params.work_fn(s); > - s->memcg_params.work_fn =3D NULL; > - > mutex_unlock(&slab_mutex); Ah, perfect catch! Thank you, Qian! Acked-by: Roman Gushchin