On 12/30/2016 02:07 PM, Jacob von Chorus wrote:
The device_unregister call in thermal_zone_device_unregister causes the
thermal_zone_device structure to be freed before the call to free the
dynamically allocated attribute groups. This leads to a kernel panic.
Could you add the following call trace:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: strlen+0x0/0x20
<snip>
Call Trace:
? kernfs_name_hash+0x17/0x80
kernfs_find_ns+0x3f/0xd0
kernfs_remove_by_name_ns+0x36/0xa0
remove_files.isra.1+0x36/0x70
sysfs_remove_group+0x44/0x90
sysfs_remove_groups+0x2e/0x50
device_remove_attrs+0x5e/0x90
device_del+0x1ea/0x350
device_unregister+0x1a/0x60
thermal_zone_device_unregister+0x1f2/0x210
pkg_thermal_cpu_offline+0x14f/0x1a0 [x86_pkg_temp_thermal]
? kzalloc.constprop.2+0x10/0x10 [x86_pkg_temp_thermal]
cpuhp_invoke_callback+0x8d/0x3f0
cpuhp_down_callbacks+0x42/0x80
cpuhp_thread_fun+0x8b/0xf0
smpboot_thread_fn+0x110/0x160
kthread+0x101/0x140
? sort_range+0x30/0x30
? kthread_park+0x90/0x90
ret_from_fork+0x25/0x30
If someone hit the kernel panic, they can find the patch from git log
more easily.
Furthermore, the 4 calls to free the trip point attribute structures
occur before the call to unregister the device, leading to a kernel
panic when sysfs attempts to access the attributes to remove them.
This patch moves the kfree calls to clean up the dynamic attributes to
the thermal_class's thermal_zone_device release function.
Cc: Zhang Rui <rui.zh...@intel.com>
Cc: Eduardo Valentin <edubez...@gmail.com>
Cc: linux...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Jacob von Chorus <jacobvoncho...@cwphoto.ca>
Tested-by: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com>
Thanks,
Yasuaki Ishimatsu
---
drivers/thermal/thermal_core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 641faab..6555913 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -799,6 +799,11 @@ static void thermal_release(struct device *dev)
if (!strncmp(dev_name(dev), "thermal_zone",
sizeof("thermal_zone") - 1)) {
tz = to_thermal_zone(dev);
+ kfree(tz->trip_type_attrs);
+ kfree(tz->trip_temp_attrs);
+ kfree(tz->trip_hyst_attrs);
+ kfree(tz->trips_attribute_group.attrs);
+ kfree(tz->device.groups);
kfree(tz);
} else if (!strncmp(dev_name(dev), "cooling_device",
sizeof("cooling_device") - 1)) {
@@ -1305,10 +1310,6 @@ void thermal_zone_device_unregister(struct
thermal_zone_device *tz)
thermal_zone_device_set_polling(tz, 0);
- kfree(tz->trip_type_attrs);
- kfree(tz->trip_temp_attrs);
- kfree(tz->trip_hyst_attrs);
- kfree(tz->trips_attribute_group.attrs);
thermal_set_governor(tz, NULL);
thermal_remove_hwmon_sysfs(tz);
@@ -1316,7 +1317,6 @@ void thermal_zone_device_unregister(struct
thermal_zone_device *tz)
idr_destroy(&tz->idr);
mutex_destroy(&tz->lock);
device_unregister(&tz->device);
- kfree(tz->device.groups);
}
EXPORT_SYMBOL_GPL(thermal_zone_device_unregister);
