4.16-stable review patch. If anyone has any objections, please let me know.
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From: Alexandre Belloni alexandre.belloni@bootlin.com
[ Upstream commit 201fac95e799c3d0304ec724d555e1251b9f6e84 ]
The probe function is not allowed to fail after registering the RTC 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* */
Switch to devm_rtc_allocate_device/rtc_register_device to register the rtc as late as possible.
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-rk808.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
--- a/drivers/rtc/rtc-rk808.c +++ b/drivers/rtc/rtc-rk808.c @@ -416,12 +416,11 @@ static int rk808_rtc_probe(struct platfo
device_init_wakeup(&pdev->dev, 1);
- rk808_rtc->rtc = devm_rtc_device_register(&pdev->dev, "rk808-rtc", - &rk808_rtc_ops, THIS_MODULE); - if (IS_ERR(rk808_rtc->rtc)) { - ret = PTR_ERR(rk808_rtc->rtc); - return ret; - } + rk808_rtc->rtc = devm_rtc_allocate_device(&pdev->dev); + if (IS_ERR(rk808_rtc->rtc)) + return PTR_ERR(rk808_rtc->rtc); + + rk808_rtc->rtc->ops = &rk808_rtc_ops;
rk808_rtc->irq = platform_get_irq(pdev, 0); if (rk808_rtc->irq < 0) { @@ -438,9 +437,10 @@ static int rk808_rtc_probe(struct platfo if (ret) { dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n", rk808_rtc->irq, ret); + return ret; }
- return ret; + return rtc_register_device(rk808_rtc->rtc); }
static struct platform_driver rk808_rtc_driver = {