thermal: core: Reference count the zone in thermal_zone_get_by_id()

commit a42a583 upstream.

There are places in the thermal netlink code where nothing prevents
the thermal zone object from going away while being accessed after it
has been returned by thermal_zone_get_by_id().

To address this, make thermal_zone_get_by_id() get a reference on the
thermal zone device object to be returned with the help of get_device(),
under thermal_list_lock, and adjust all of its callers to this change
with the help of the cleanup.h infrastructure.

Fixes: 1ce50e7 ("thermal: core: genetlink support for events/cmd/sampling")
Cc: 6.8+ <stable@vger.kernel.org> # 6.8+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://patch.msgid.link/6112242.lOV4Wx5bFT@rjwysocki.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: rafaeljw

drivers/thermal/thermal_core.c

@@ -737,6 +737,7 @@ struct thermal_zone_device *thermal_zone_get_by_id(int id)
 	mutex_lock(&thermal_list_lock);
 	list_for_each_entry(tz, &thermal_tz_list, node) {
 		if (tz->id == id) {
+			get_device(&tz->device);
 			match = tz;
 			break;
 		}

drivers/thermal/thermal_core.h

@@ -194,6 +194,9 @@ int for_each_thermal_governor(int (*cb)(struct thermal_governor *, void *),
 
 struct thermal_zone_device *thermal_zone_get_by_id(int id);
 
+DEFINE_CLASS(thermal_zone_get_by_id, struct thermal_zone_device *,
+	     if (_T) put_device(&_T->device), thermal_zone_get_by_id(id), int id)
+
 static inline bool cdev_is_power_actor(struct thermal_cooling_device *cdev)
 {
 	return cdev->ops->get_requested_power && cdev->ops->state2power &&

drivers/thermal/thermal_netlink.c

@@ -443,7 +443,6 @@ static int thermal_genl_cmd_tz_get_trip(struct param *p)
 {
 	struct sk_buff *msg = p->msg;
 	const struct thermal_trip_desc *td;
-	struct thermal_zone_device *tz;
 	struct nlattr *start_trip;
 	int id;
 
@@ -452,7 +451,7 @@ static int thermal_genl_cmd_tz_get_trip(struct param *p)
 
 	id = nla_get_u32(p->attrs[THERMAL_GENL_ATTR_TZ_ID]);
 
-	tz = thermal_zone_get_by_id(id);
+	CLASS(thermal_zone_get_by_id, tz)(id);
 	if (!tz)
 		return -EINVAL;
 
@@ -488,15 +487,14 @@ static int thermal_genl_cmd_tz_get_trip(struct param *p)
 static int thermal_genl_cmd_tz_get_temp(struct param *p)
 {
 	struct sk_buff *msg = p->msg;
-	struct thermal_zone_device *tz;
 	int temp, ret, id;
 
 	if (!p->attrs[THERMAL_GENL_ATTR_TZ_ID])
 		return -EINVAL;
 
 	id = nla_get_u32(p->attrs[THERMAL_GENL_ATTR_TZ_ID]);
 
-	tz = thermal_zone_get_by_id(id);
+	CLASS(thermal_zone_get_by_id, tz)(id);
 	if (!tz)
 		return -EINVAL;
 
@@ -514,15 +512,14 @@ static int thermal_genl_cmd_tz_get_temp(struct param *p)
 static int thermal_genl_cmd_tz_get_gov(struct param *p)
 {
 	struct sk_buff *msg = p->msg;
-	struct thermal_zone_device *tz;
 	int id, ret = 0;
 
 	if (!p->attrs[THERMAL_GENL_ATTR_TZ_ID])
 		return -EINVAL;
 
 	id = nla_get_u32(p->attrs[THERMAL_GENL_ATTR_TZ_ID]);
 
-	tz = thermal_zone_get_by_id(id);
+	CLASS(thermal_zone_get_by_id, tz)(id);
 	if (!tz)
 		return -EINVAL;