thermal: check for invalid trip setup when registering thermal device

This patch adds an extra check in the data structure while registering
a thermal device. The check is to avoid registering zones with a number
of trips greater than zero, but with no .get_trip_temp nor .get_trip_type
callbacks. Receiving such data structure may end in wrong data access.

Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
Reviewed-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/thermal_sys.c

@@ -1530,6 +1530,9 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	if (!ops || !ops->get_temp)
 		return ERR_PTR(-EINVAL);
 
+	if (trips > 0 && !ops->get_trip_type)
+		return ERR_PTR(-EINVAL);
+
 	tz = kzalloc(sizeof(struct thermal_zone_device), GFP_KERNEL);
 	if (!tz)
 		return ERR_PTR(-ENOMEM);