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

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: 1ce50e7d408e ("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

3 files changed, 7 insertions, 6 deletions

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 073d02e21352..c69f8123fb73 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -728,6 +728,7 @@ 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;
 		}
diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 50b858aa173a..a64d39b1c86b 100644
--- a/drivers/thermal/thermal_core.h
+++ b/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 &&
diff --git a/drivers/thermal/thermal_netlink.c b/drivers/thermal/thermal_netlink.c
index 97157c453630..f3c58c708969 100644
--- a/drivers/thermal/thermal_netlink.c
+++ b/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;
 
@@ -488,7 +487,6 @@ out_cancel_nest:
 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])
@@ -496,7 +494,7 @@ static int thermal_genl_cmd_tz_get_temp(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;
 
@@ -514,7 +512,6 @@ 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])
@@ -522,7 +519,7 @@ static int thermal_genl_cmd_tz_get_gov(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;