drm/radeon: implement bounds checking on thermal controller lookup

Don't read past the end of the array if we encounter an unknown
thermal controller.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -2009,7 +2009,8 @@ static int radeon_atombios_parse_power_table_1_3(struct radeon_device *rdev)
 	power_info = (union power_info *)(mode_info->atom_context->bios + data_offset);
 
 	/* add the i2c bus for thermal/fan chip */
-	if (power_info->info.ucOverdriveThermalController > 0) {
+	if ((power_info->info.ucOverdriveThermalController > 0) &&
+	    (power_info->info.ucOverdriveThermalController < ARRAY_SIZE(thermal_controller_names))) {
 		DRM_INFO("Possible %s thermal controller at 0x%02x\n",
 			 thermal_controller_names[power_info->info.ucOverdriveThermalController],
 			 power_info->info.ucOverdriveControllerAddress >> 1);
@@ -2213,7 +2214,7 @@ static void radeon_atombios_add_pplib_thermal_controller(struct radeon_device *r
 			   (controller->ucType ==
 			    ATOM_PP_THERMALCONTROLLER_EMC2103_WITH_INTERNAL)) {
 			DRM_INFO("Special thermal controller config\n");
-		} else {
+		} else if (controller->ucType < ARRAY_SIZE(pp_lib_thermal_controller_names)) {
 			DRM_INFO("Possible %s thermal controller at 0x%02x %s fan control\n",
 				 pp_lib_thermal_controller_names[controller->ucType],
 				 controller->ucI2cAddress >> 1,
@@ -2228,6 +2229,12 @@ static void radeon_atombios_add_pplib_thermal_controller(struct radeon_device *r
 				strlcpy(info.type, name, sizeof(info.type));
 				i2c_new_device(&rdev->pm.i2c_bus->adapter, &info);
 			}
+		} else {
+			DRM_INFO("Unknown thermal controller type %d at 0x%02x %s fan control\n",
+				 controller->ucType,
+				 controller->ucI2cAddress >> 1,
+				 (controller->ucFanParameters &
+				  ATOM_PP_FANPARAMETERS_NOFAN) ? "without" : "with");
 		}
 	}
 }