4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alexandre Belloni alexandre.belloni@bootlin.com
[ Upstream commit 9a99247c9c1d1c95c6e8153d013979aac6111c6e ]
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 alexandre.belloni@bootlin.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/rtc/rtc-vr41xx.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/drivers/rtc/rtc-vr41xx.c +++ b/drivers/rtc/rtc-vr41xx.c @@ -292,13 +292,14 @@ static int rtc_probe(struct platform_dev 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_dev
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: