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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6C99C43217 for ; Wed, 19 Oct 2022 02:26:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229942AbiJSC02 (ORCPT ); Tue, 18 Oct 2022 22:26:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229848AbiJSC0X (ORCPT ); Tue, 18 Oct 2022 22:26:23 -0400 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2C016A4B1 for ; Tue, 18 Oct 2022 19:26:20 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R661e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045176;MF=joseph.qi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0VSYJtJM_1666146375; Received: from 30.221.128.228(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0VSYJtJM_1666146375) by smtp.aliyun-inc.com; Wed, 19 Oct 2022 10:26:17 +0800 Message-ID: <1adbbf98-2700-27c8-4aca-9510bca91458@linux.alibaba.com> Date: Wed, 19 Oct 2022 10:26:15 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.3.3 Subject: Re: [PATCH] ocfs2: possible memory leak in mlog_sys_init() To: Yang Yingliang , linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com Cc: mark@fasheh.com, jlbec@evilplan.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org References: <20221018075213.736562-1-yangyingliang@huawei.com> <09bb2844-e20a-98e8-c2af-5b6c4795d48e@huawei.com> <0db486eb-6927-927e-3629-958f8f211194@huawei.com> Content-Language: en-US From: Joseph Qi In-Reply-To: <0db486eb-6927-927e-3629-958f8f211194@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/18/22 10:28 PM, Yang Yingliang wrote: > > On 2022/10/18 21:39, Joseph Qi wrote: >> >> On 10/18/22 6:33 PM, Yang Yingliang wrote: >>> Hi, >>> >>> On 2022/10/18 17:02, Joseph Qi wrote: >>>> Hi, >>>> >>>> On 10/18/22 3:52 PM, Yang Yingliang wrote: >>>>> Inject fault while probing module, kset_register() may fail, >>>>> if it fails, but the refcount of kobject is not decreased to >>>>> 0, the name allocated in kobject_set_name() is leaked. Fix >>>>> this by calling kset_put(), so that name can be freed in >>>>> callback function kobject_cleanup(). >>>>> >>>>> unreferenced object 0xffff888100da9348 (size 8): >>>>>     comm "modprobe", pid 257, jiffies 4294701096 (age 33.334s) >>>>>     hex dump (first 8 bytes): >>>>>       6c 6f 67 6d 61 73 6b 00                          logmask. >>>>>     backtrace: >>>>>       [<00000000306e441c>] __kmalloc_node_track_caller+0x44/0x1b0 >>>>>       [<000000007c491a9e>] kstrdup+0x3a/0x70 >>>>>       [<0000000015719a3b>] kstrdup_const+0x63/0x80 >>>>>       [<0000000084e458ea>] kvasprintf_const+0x149/0x180 >>>>>       [<0000000091302b42>] kobject_set_name_vargs+0x56/0x150 >>>>>       [<000000005f48eeac>] kobject_set_name+0xab/0xe0 >>>>> >>>>> Fixes: 34980ca8faeb ("Drivers: clean up direct setting of the name of a kset") >>>>> Signed-off-by: Yang Yingliang >>>>> --- >>>>>    fs/ocfs2/cluster/masklog.c | 7 ++++++- >>>>>    1 file changed, 6 insertions(+), 1 deletion(-) >>>>> >>>>> diff --git a/fs/ocfs2/cluster/masklog.c b/fs/ocfs2/cluster/masklog.c >>>>> index 563881ddbf00..7f9ba816d955 100644 >>>>> --- a/fs/ocfs2/cluster/masklog.c >>>>> +++ b/fs/ocfs2/cluster/masklog.c >>>>> @@ -156,6 +156,7 @@ static struct kset mlog_kset = { >>>>>    int mlog_sys_init(struct kset *o2cb_kset) >>>>>    { >>>>>        int i = 0; >>>>> +    int ret; >>>>>          while (mlog_attrs[i].attr.mode) { >>>>>            mlog_default_attrs[i] = &mlog_attrs[i].attr; >>>>> @@ -165,7 +166,11 @@ int mlog_sys_init(struct kset *o2cb_kset) >>>>>          kobject_set_name(&mlog_kset.kobj, "logmask"); >>>>>        mlog_kset.kobj.kset = o2cb_kset; >>>>> -    return kset_register(&mlog_kset); >>>>> +    ret = kset_register(&mlog_kset); >>>> If register fails, it will call unregister in o2cb_sys_init(), which >>>> will put kobject. >>> They are different ksets, the kset unregistered in o2cb_sys_init() is 'o2cb_kset', the >>> kset used to registered in mlog_sys_init() is 'mlog_kset', and they hold difference >>> refcounts. >>> Yes, you are right. I've mixed the two ksets up. >> In theory, kset_register() may return error because of a NULL kset, so >> here we may not call kset_put() directly, I'm not sure if a static >> checker will happy. >> Though this can't happen since it's already statically allocated... > kset_register() may fail if kobject_add_internal() return error (can't allocate memory), the name > "logmask" is dynamically alloctated while ocfs2 is compile as module and insert it (if ocfs2 is > built in kernel, the name is constant, it won't cause a leak), so the name can be leaked. What I mean is kset_register() may fail with many reasons, or even without kset_init(). I wonder if we have to handle this internal kset_register(), but not leave it to caller. This may benefit other callers as well. Something like: err = kobject_add_internal(&k->kobj); if (err) { kset_put(k); return err; } Thanks, Joseph