thermal: core: Fix thermal zone governor cleanup issues

If thermal_zone_device_register_with_trips() fails after adding
a thermal governor to the thermal zone being registered, the
governor is not removed from it as appropriate which may lead to
a memory leak.

In turn, thermal_zone_device_unregister() calls thermal_set_governor()
without acquiring the thermal zone lock beforehand which may race with
a governor update via sysfs and may lead to a use-after-free in that
case.

Address these issues by adding two thermal_set_governor() calls, one to
thermal_release() to remove the governor from the given thermal zone,
and one to the thermal zone registration error path to cover failures
preceding the thermal zone device registration.

Fixes: e33df1d ("thermal: let governors have private data for each thermal zone")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/5092923.31r3eYUQgx@rafael.j.wysocki

Author: rafaeljw

drivers/thermal/thermal_core.c

@@ -964,6 +964,7 @@ static void thermal_release(struct device *dev)
 		     sizeof("thermal_zone") - 1)) {
 		tz = to_thermal_zone(dev);
 		thermal_zone_destroy_device_groups(tz);
+		thermal_set_governor(tz, NULL);
 		mutex_destroy(&tz->lock);
 		complete(&tz->removal);
 	} else if (!strncmp(dev_name(dev), "cooling_device",
@@ -1610,8 +1611,10 @@ thermal_zone_device_register_with_trips(const char *type,
 	/* sys I/F */
 	/* Add nodes that are always present via .groups */
 	result = thermal_zone_create_device_groups(tz);
-	if (result)
+	if (result) {
+		thermal_set_governor(tz, NULL);
 		goto remove_id;
+	}
 
 	result = device_register(&tz->device);
 	if (result)
@@ -1724,8 +1727,6 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 
 	cancel_delayed_work_sync(&tz->poll_queue);
 
-	thermal_set_governor(tz, NULL);
-
 	thermal_thresholds_exit(tz);
 	thermal_remove_hwmon_sysfs(tz);
 	ida_free(&thermal_tz_ida, tz->id);