From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3A72C4321D for ; Mon, 20 Aug 2018 17:12:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 668C720C0C for ; Mon, 20 Aug 2018 17:12:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 668C720C0C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.vnet.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727318AbeHTU2g (ORCPT ); Mon, 20 Aug 2018 16:28:36 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:59238 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726201AbeHTU2g (ORCPT ); Mon, 20 Aug 2018 16:28:36 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w7KHBwmY026559 for ; Mon, 20 Aug 2018 13:12:08 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2m010vhy5a-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 20 Aug 2018 13:12:01 -0400 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 20 Aug 2018 18:10:00 +0100 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w7KH9x3E29294700 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 20 Aug 2018 17:09:59 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DCAD44203F; Mon, 20 Aug 2018 20:10:01 +0100 (BST) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6B4F242042; Mon, 20 Aug 2018 20:10:00 +0100 (BST) Received: from srikart450.in.ibm.com (unknown [9.124.212.101]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 20 Aug 2018 20:10:00 +0100 (BST) From: Srikar Dronamraju To: LKML , Greg Kroah-Hartman , Andrew Morton , Linus Torvalds Cc: Srikar Dronamraju , Dmitry Torokhov , "David S . Miller" Subject: [PATCH] kobject: Access kobject name with caution if state is not initialized Date: Mon, 20 Aug 2018 22:39:47 +0530 X-Mailer: git-send-email 2.7.4 X-TM-AS-GCONF: 00 x-cbid: 18082017-0008-0000-0000-000002644E01 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18082017-0009-0000-0000-000021CC88F7 Message-Id: <1534784987-16107-1-git-send-email-srikar@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-08-20_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound 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=8.0.1-1807170000 definitions=main-1808200179 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If kobject state is not initialized, then its not even certain that kobject'name is initialized. Hence when accessing the kobject's name tread carefully. A stupid module test like https://github.com/srikard/tests/blob/master/modules/kobject_test.c can panic the system. With patch: We will see the correct warning. [ 2058.129913] ------------[ cut here ]------------ [ 2058.129919] kobject: ' ' (00000000ad405b63): is not initialized, yet kobject_get() is being called. [ 2058.129938] WARNING: CPU: 58 PID: 18529 at /home/srikar/work/linux.git/lib/kobject.c:620 kobject_get+0x90/0xb0 [ 2058.129946] Modules linked in: kobject_test(OE+) uio_pdrv_genirq(E) uio(E) leds_powernv(E) powernv_op_panel(E) ipmi_powernv(E) ipmi_devintf(E) powernv_rng(E) ibmpowernv(E) ipmi_msghandler(E) vmx_crypto(E) crct10dif_vpmsum(E) sch_fq_codel(E) ip_tables(E) x_tables(E) autofs4(E) ses enclosure scsi_transport_sas mlx4_ib mlx4_en ib_core lpfc crc32c_vpmsum mlx4_core nvmet_fc nvmet nvme_fc ipr nvme_fabrics devlink scsi_transport_fc tg3 [last unloaded: module_test] [ 2058.130014] CPU: 58 PID: 18529 Comm: insmod Tainted: G W OEL 4.18.0-master+ #3 [ 2058.130022] NIP: c000000000d5f530 LR: c000000000d5f52c CTR: 0000000000000000 [ 2058.130029] REGS: c000002fd32f3640 TRAP: 0700 Tainted: G W OEL (4.18.0-master+) [ 2058.130036] MSR: 9000000002029033 CR: 48002282 XER: 20000000 [ 2058.130054] CFAR: c000000000114e10 IRQMASK: 0 GPR00: c000000000d5f52c c000002fd32f38c0 c0000000017bc200 0000000000000057 GPR04: 0000000000000001 000000000000107e 9000000002009033 00000000000000f2 GPR08: 0000000000000007 0000000000000007 0000000000000001 9000000002001003 GPR12: 0000000000002200 c000002ffffe0d00 0000000000000000 0000000000000000 GPR16: 0000000000000000 c0000000001e92e0 0000000000000000 0000000000000100 GPR20: 0000000000000001 c000000001662e60 c000000001662ed8 c000002feb4114a0 GPR24: 0000000000000001 c000000000dbd438 c000000001662ea0 c000000001662ec0 GPR28: c000002fe5f0cea0 d00000001ded03d0 c000002fd32f39a0 c000002fd32f39a0 [ 2058.130133] NIP [c000000000d5f530] kobject_get+0x90/0xb0 [ 2058.130140] LR [c000000000d5f52c] kobject_get+0x8c/0xb0 [ 2058.130146] Call Trace: [ 2058.130150] [c000002fd32f38c0] [c000000000d5f52c] kobject_get+0x8c/0xb0 (unreliable) [ 2058.130159] [c000002fd32f3940] [d00000001ded0088] kobject_test_init+0x80/0xb0 [kobject_test] [ 2058.130168] [c000002fd32f39f0] [c0000000000101f8] do_one_initcall+0x58/0x240 [ 2058.130178] [c000002fd32f3ab0] [c0000000001ef2b0] do_init_module+0x90/0x260 [ 2058.130186] [c000002fd32f3b40] [c0000000001edec8] load_module+0x2d88/0x3320 [ 2058.130193] [c000002fd32f3d20] [c0000000001ee764] sys_finit_module+0xc4/0x130 [ 2058.130204] [c000002fd32f3e30] [c00000000000b288] system_call+0x5c/0x70 [ 2058.130210] Instruction dump: [ 2058.130215] e89f0000 4b5b4c15 60000000 2f830000 419e0030 3c82ff8c 388491e0 3c62ff90 [ 2058.130228] 7fe5fb78 3863e9b0 4b3b5881 60000000 <0fe00000> e8010090 7c0803a6 4bffff88 [ 2058.130240] ---[ end trace 0f471c192555a013 ]--- [ 2070.084234] kobject_test module unloaded Signed-off-by: Srikar Dronamraju --- lib/kobject.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/lib/kobject.c b/lib/kobject.c index 389829d3a1d1..2d65be37fd7b 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -16,6 +16,7 @@ #include #include #include +#include /** * kobject_namespace - return @kobj's namespace tag @@ -417,8 +418,11 @@ int kobject_add(struct kobject *kobj, struct kobject *parent, return -EINVAL; if (!kobj->state_initialized) { + char tmp; + int ret = probe_kernel_address(kobject_name(kobj), tmp); + pr_err("kobject '%s' (%p): tried to add an uninitialized object, something is seriously wrong.\n", - kobject_name(kobj), kobj); + ret ? " " : kobject_name(kobj), kobj); dump_stack(); return -EINVAL; } @@ -606,10 +610,14 @@ EXPORT_SYMBOL(kobject_del); struct kobject *kobject_get(struct kobject *kobj) { if (kobj) { - if (!kobj->state_initialized) + if (!kobj->state_initialized) { + char tmp; + int ret = probe_kernel_address(kobject_name(kobj), tmp); + WARN(1, KERN_WARNING "kobject: '%s' (%p): is not initialized, yet kobject_get() is being called.\n", - kobject_name(kobj), kobj); + ret ? " " : kobject_name(kobj), kobj); + } kref_get(&kobj->kref); } return kobj; @@ -701,10 +709,14 @@ static void kobject_release(struct kref *kref) void kobject_put(struct kobject *kobj) { if (kobj) { - if (!kobj->state_initialized) + if (!kobj->state_initialized) { + char tmp; + int ret = probe_kernel_address(kobject_name(kobj), tmp); + WARN(1, KERN_WARNING "kobject: '%s' (%p): is not initialized, yet kobject_put() is being called.\n", - kobject_name(kobj), kobj); + ret ? " " : kobject_name(kobj), kobj); + } kref_put(&kobj->kref, kobject_release); } } -- 2.17.1