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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89E08C433FE for ; Mon, 11 Oct 2021 09:40:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7234C60231 for ; Mon, 11 Oct 2021 09:40:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235591AbhJKJmj (ORCPT ); Mon, 11 Oct 2021 05:42:39 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:13718 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235572AbhJKJmh (ORCPT ); Mon, 11 Oct 2021 05:42:37 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4HSYdw44jWzWWfs; Mon, 11 Oct 2021 17:39:00 +0800 (CST) Received: from dggpeml500017.china.huawei.com (7.185.36.243) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Mon, 11 Oct 2021 17:40:35 +0800 Received: from [10.174.178.174] (10.174.178.174) by dggpeml500017.china.huawei.com (7.185.36.243) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Mon, 11 Oct 2021 17:40:35 +0800 Subject: Re: [PATCH 2/2] rtc: class: return error code when cdev_device_add() failed To: Alexandre Belloni CC: , , References: <20211011080302.1982894-1-yangyingliang@huawei.com> <20211011080302.1982894-2-yangyingliang@huawei.com> From: Yang Yingliang Message-ID: <6fcea87c-b44a-2045-9644-dce4eb968c68@huawei.com> Date: Mon, 11 Oct 2021 17:40:34 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpeml500017.china.huawei.com (7.185.36.243) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2021/10/11 16:36, Alexandre Belloni wrote: > On 11/10/2021 16:03:02+0800, Yang Yingliang wrote: >> I got a null-ptr-deref report when doing fault injection test: >> >> general protection fault, probably for non-canonical address 0xdffffc0000000022: 0000 [#1] SMP KASAN PTI >> KASAN: null-ptr-deref in range [0x0000000000000110-0x0000000000000117] >> CPU: 1 PID: 1028 Comm: 33 Not tainted 5.15.0-rc3-00111-gf5dad42ed4fe-dirty #481 2a70b3e6ca240b8638beac7ef491cce6183bbec7 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 >> RIP: 0010:device_del+0x132/0xdc0 >> Code: 48 c1 ea 03 80 3c 02 00 0f 85 4f 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 7b 48 4d 8d a7 10 01 00 00 4c 89 e2 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e 7f 0a 00 00 45 0f b6 b7 10 01 00 00 >> RSP: 0018:ffffc90002e876b8 EFLAGS: 00010206 >> RAX: dffffc0000000000 RBX: ffff88801eb84000 RCX: ffffffff97227644 >> RDX: 0000000000000022 RSI: ffff8880146a0000 RDI: 0000000000000002 >> RBP: ffff88801eb84120 R08: fffffbfff349a60d R09: fffffbfff349a60d >> R10: ffffc90002e876b8 R11: fffffbfff349a60c R12: 0000000000000110 >> R13: 0000000000000001 R14: ffffc90002e87848 R15: 0000000000000000 >> FS: 00007fa514973500(0000) GS:ffff888104600000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 00007fa51474ccb0 CR3: 000000002bcb0001 CR4: 0000000000770ee0 >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> PKRU: 55555554 >> Call Trace: >> ? write_comp_data+0x2a/0x90 >> ? cleanup_glue_dir+0x260/0x260 >> ? is_rtc_hctosys.isra.0+0xb9/0xf0 >> ? rtc_proc_show+0x440/0x440 >> ? rcu_read_lock_held_common+0xe/0xa0 >> ? rcu_read_lock_sched_held+0x62/0xe0 >> cdev_device_del+0x1a/0x80 >> devm_rtc_unregister_device+0x37/0x80 >> release_nodes+0xc3/0x3b0 >> >> If cdev_device_add() fails, 'dev->p' is not set, it causes >> null-ptr-deref when calling cdev_device_del(), return error >> code when cdev_device_add() failed to fix this. >> >> Reported-by: Hulk Robot >> Fixes: 3068a254d5519 ("rtc: introduce new registration method") >> Signed-off-by: Yang Yingliang >> --- >> drivers/rtc/class.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c >> index 1f18c39a4b82..76422faee05b 100644 >> --- a/drivers/rtc/class.c >> +++ b/drivers/rtc/class.c >> @@ -399,12 +399,14 @@ int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc) >> rtc_dev_prepare(rtc); >> >> err = cdev_device_add(&rtc->char_dev, &rtc->dev); >> - if (err) >> + if (err) { >> dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n", >> MAJOR(rtc->dev.devt), rtc->id); >> - else >> + return err; > As the checkpatch warning indicates, registering the character device as > always been optional. d5ed9177f64fe95d9de79e6504d41612d9127e8a is the > commit you want to fix. So we can keep doing rtc register, even if cdev_device_add() failed ? Thanks, Yang > >> + } else { >> dev_dbg(rtc->dev.parent, "char device (%d:%d)\n", >> MAJOR(rtc->dev.devt), rtc->id); >> + } >> >> rtc_proc_add_device(rtc); >> >> -- >> 2.25.1 >>