From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752219AbeEQUrN (ORCPT ); Thu, 17 May 2018 16:47:13 -0400 Received: from mail.bootlin.com ([62.4.15.54]:39325 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751017AbeEQUrJ (ORCPT ); Thu, 17 May 2018 16:47:09 -0400 From: Alexandre Belloni To: linux-rtc@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Alexandre Belloni Subject: [PATCH 1/2] rtc: vr41xx: fix possible race condition Date: Thu, 17 May 2018 22:47:05 +0200 Message-Id: <20180517204706.28192-1-alexandre.belloni@bootlin.com> X-Mailer: git-send-email 2.17.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The probe function is not allowed to fail after the RTC is registered because the following may happen: CPU0: CPU1: sys_load_module() do_init_module() do_one_initcall() cmos_do_probe() rtc_device_register() __register_chrdev() cdev->owner = struct module* open("/dev/rtc0") rtc_device_unregister() module_put() free_module() module_free(mod->module_core) /* struct module *module is now freed */ chrdev_open() spin_lock(cdev_lock) cdev_get() try_module_get() module_is_live() /* dereferences already freed struct module* */ Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-vr41xx.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/rtc-vr41xx.c b/drivers/rtc/rtc-vr41xx.c index 480cffe8d321..2f1212a25f7e 100644 --- a/drivers/rtc/rtc-vr41xx.c +++ b/drivers/rtc/rtc-vr41xx.c @@ -292,13 +292,14 @@ static int rtc_probe(struct platform_device *pdev) goto err_rtc1_iounmap; } - rtc = devm_rtc_device_register(&pdev->dev, rtc_name, &vr41xx_rtc_ops, - THIS_MODULE); + rtc = devm_rtc_allocate_device(&pdev->dev); if (IS_ERR(rtc)) { retval = PTR_ERR(rtc); goto err_iounmap_all; } + rtc->ops = &vr41xx_rtc_ops; + rtc->max_user_freq = MAX_PERIODIC_RATE; spin_lock_irq(&rtc_lock); @@ -340,6 +341,10 @@ static int rtc_probe(struct platform_device *pdev) dev_info(&pdev->dev, "Real Time Clock of NEC VR4100 series\n"); + retval = rtc_register_device(rtc); + if (retval) + goto err_iounmap_all; + return 0; err_iounmap_all: -- 2.17.0