When offlining all cores on a CPU, the following system panic occurs:
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 thermal_zone_create_device_group() sets attribute_groups in thermal_zone_attribute_groups[] to tz->device.groups. But these attributes_groups do not have name argument. So when offlining all cores on CPU and executing thermal_zone_device_unregister(), the panic occurs in strlen() called from kernfs_name_hash() because name argument is NULL. The patch adds thermal_zone_remove_device_groups() to free tz->device.groups and set NULL pointer. Signed-off-by: Yasuaki Ishimatsu <[email protected]> CC: Zhang Rui <[email protected]> CC: Eduardo Valentin <[email protected]> --- drivers/thermal/thermal_core.c | 3 ++- drivers/thermal/thermal_core.h | 1 + drivers/thermal/thermal_sysfs.c | 6 ++++++ 3 files changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c index 641faab..926e385 100644 --- a/drivers/thermal/thermal_core.c +++ b/drivers/thermal/thermal_core.c @@ -1251,6 +1251,7 @@ struct thermal_zone_device * unregister: release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id); + thermal_zone_remove_device_groups(tz); device_unregister(&tz->device); return ERR_PTR(result); } @@ -1315,8 +1316,8 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz) release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id); idr_destroy(&tz->idr); mutex_destroy(&tz->lock); + thermal_zone_remove_device_groups(tz); device_unregister(&tz->device); - kfree(tz->device.groups); } EXPORT_SYMBOL_GPL(thermal_zone_device_unregister); diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h index 2412b37..e3a60db 100644 --- a/drivers/thermal/thermal_core.h +++ b/drivers/thermal/thermal_core.h @@ -70,6 +70,7 @@ void thermal_zone_device_unbind_exception(struct thermal_zone_device *, int thermal_build_list_of_policies(char *buf); /* sysfs I/F */ +void thermal_zone_remove_device_groups(struct thermal_zone_device *tz); int thermal_zone_create_device_groups(struct thermal_zone_device *, int); void thermal_cooling_device_setup_sysfs(struct thermal_cooling_device *); /* used only at binding time */ diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c index a694de9..3dfd29b 100644 --- a/drivers/thermal/thermal_sysfs.c +++ b/drivers/thermal/thermal_sysfs.c @@ -605,6 +605,12 @@ static int create_trip_attrs(struct thermal_zone_device *tz, int mask) return 0; } +void thermal_zone_remove_device_groups(struct thermal_zone_device *tz) +{ + kfree(tz->device.groups); + tz->device.groups = NULL; +} + int thermal_zone_create_device_groups(struct thermal_zone_device *tz, int mask) { -- 1.8.3.1
