4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alexandre Belloni alexandre.belloni@bootlin.com
[ Upstream commit bcdd559268039d8340d38fa58668393596e29fdc ]
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-rp5c01.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
--- a/drivers/rtc/rtc-rp5c01.c +++ b/drivers/rtc/rtc-rp5c01.c @@ -249,16 +249,24 @@ static int __init rp5c01_rtc_probe(struc
platform_set_drvdata(dev, priv);
- rtc = devm_rtc_device_register(&dev->dev, "rtc-rp5c01", &rp5c01_rtc_ops, - THIS_MODULE); + rtc = devm_rtc_allocate_device(&dev->dev); if (IS_ERR(rtc)) return PTR_ERR(rtc); + + rtc->ops = &rp5c01_rtc_ops; + priv->rtc = rtc;
error = sysfs_create_bin_file(&dev->dev.kobj, &priv->nvram_attr); if (error) return error;
+ error = rtc_register_device(rtc); + if (error) { + sysfs_remove_bin_file(&dev->dev.kobj, &priv->nvram_attr); + return error; + } + return 0; }