4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
[ 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@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
