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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 30316C43381 for ; Sat, 9 Mar 2019 04:13:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02A032081B for ; Sat, 9 Mar 2019 04:13:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726610AbfCIENh (ORCPT ); Fri, 8 Mar 2019 23:13:37 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:4661 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726375AbfCIENg (ORCPT ); Fri, 8 Mar 2019 23:13:36 -0500 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id EC924E5BFBF796934EA7; Sat, 9 Mar 2019 12:13:33 +0800 (CST) Received: from [127.0.0.1] (10.177.19.180) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.408.0; Sat, 9 Mar 2019 12:13:31 +0800 Subject: Re: [PATCH] workqueue: unregister wq lockdep on error path in alloc_workqueue() To: Bart Van Assche , Ingo Molnar , Tejun Heo , CC: References: <20190308073713.39853-1-wangkefeng.wang@huawei.com> <150578a7-f053-a479-2b1a-34279c93fc4b@acm.org> From: Kefeng Wang Message-ID: <9fb0213e-efc2-ec7f-b257-d0c851e67025@huawei.com> Date: Sat, 9 Mar 2019 12:13:30 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <150578a7-f053-a479-2b1a-34279c93fc4b@acm.org> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.177.19.180] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/3/8 22:45, Bart Van Assche wrote: > On 3/7/19 11:37 PM, Kefeng Wang wrote: >> syzkaller report an issue "KASAN: use-after-free Read in alloc_workqueue", >> >> alloc_workqueue >>   - kzalloc wq >>   - wq_init_lockdep(wq); >>     - lockdep_register_key(&wq->key);  // add to hlist >>   - kfree wq >> >> But forget to call wq_unregister_lockdep()->lockdep_unregister_key(), it >> will delete the entry from hlist. >> >> Reported-by: syzbot+17335689e239ce135d8b@syzkaller.appspotmail.com >> Fixes: 669de8bda87b ("kernel/workqueue: Use dynamic lockdep keys for workqueues") >> Signed-off-by: Kefeng Wang >> --- >>   kernel/workqueue.c | 1 + >>   1 file changed, 1 insertion(+) >> >> diff --git a/kernel/workqueue.c b/kernel/workqueue.c >> index 7abbeed13421..9209d25dfade 100644 >> --- a/kernel/workqueue.c >> +++ b/kernel/workqueue.c >> @@ -4291,6 +4291,7 @@ struct workqueue_struct *alloc_workqueue(const char *fmt, >>       return wq; >>     err_free_wq: >> +    wq_unregister_lockdep(wq); >>       free_workqueue_attrs(wq->unbound_attrs); >>       kfree(wq); >>       return NULL; > > Hi Kefeng, > > Five days ago I had posted a similar but slightly different patch. Can you have a look at it? See also https://lore.kernel.org/lkml/20190303220046.29448-1-bvanassche@acm.org/  I don't notice your patch due to no subscribe lkml,  that is better, wq->lock_name should be freed too; ) > > Thanks, > > Bart. > > > > . >