From patchwork Mon Oct 11 13:21:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yang Yingliang X-Patchwork-Id: 1539305 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-rtc-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by bilbo.ozlabs.org (Postfix) with ESMTP id 4HSfPS5CK3z9sP7 for ; Tue, 12 Oct 2021 00:13:32 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235534AbhJKNP3 (ORCPT ); Mon, 11 Oct 2021 09:15:29 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:13719 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231538AbhJKNP1 (ORCPT ); Mon, 11 Oct 2021 09:15:27 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4HSfMV6DbvzWZ7G; Mon, 11 Oct 2021 21:11:50 +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 21:13:25 +0800 Received: from huawei.com (10.175.103.91) 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 21:13:25 +0800 From: Yang Yingliang To: , CC: , Subject: [PATCH] rtc: class: don't call cdev_device_del() when cdev_device_add() failed Date: Mon, 11 Oct 2021 21:21:14 +0800 Message-ID: <20211011132114.3663509-1-yangyingliang@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.103.91] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpeml500017.china.huawei.com (7.185.36.243) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org 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] RIP: 0010:device_del+0x132/0xdc0 Call Trace: 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(). Registering character device is optional, we don't return error code here, so introduce a new flag 'RTC_NO_CDEV' to indicate if it has character device, cdev_device_del() is called when this bit is not set. Reported-by: Hulk Robot Signed-off-by: Yang Yingliang --- drivers/rtc/class.c | 9 ++++++--- include/linux/rtc.h | 1 + 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c index 1f18c39a4b82..dbccd71589b9 100644 --- a/drivers/rtc/class.c +++ b/drivers/rtc/class.c @@ -334,7 +334,8 @@ static void devm_rtc_unregister_device(void *data) * letting any rtc_class_open() users access it again */ rtc_proc_del_device(rtc); - cdev_device_del(&rtc->char_dev, &rtc->dev); + if (!test_bit(RTC_NO_CDEV, &rtc->flags)) + cdev_device_del(&rtc->char_dev, &rtc->dev); rtc->ops = NULL; mutex_unlock(&rtc->ops_lock); } @@ -399,12 +400,14 @@ 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) { + set_bit(RTC_NO_CDEV, &rtc->flags); dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n", MAJOR(rtc->dev.devt), rtc->id); - else + } else { dev_dbg(rtc->dev.parent, "char device (%d:%d)\n", MAJOR(rtc->dev.devt), rtc->id); + } rtc_proc_add_device(rtc); diff --git a/include/linux/rtc.h b/include/linux/rtc.h index bd611e26291d..354e0843ab17 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -80,6 +80,7 @@ struct rtc_timer { /* flags */ #define RTC_DEV_BUSY 0 +#define RTC_NO_CDEV 1 struct rtc_device { struct device dev;