efi_loader: Check for a valid fw_name before auto generating GUIDs

The gen_v5_guid() is a void and does no error checking with pointers
being available etc. Instead it expects all things to be in place to
generate GUIDs. If a board capsule definition is buggy and does not
define the firmware names when enabling capsule updates, the board will
crash trying to bring up the EFI subsystem.

Check for a valid firmware name before generating GUIDs.

Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

lib/efi_loader/efi_firmware.c

@@ -281,6 +281,10 @@ static efi_status_t efi_gen_capsule_guids(void)
 	}
 
 	for (i = 0; i < update_info.num_images; i++) {
+		if (!fw_array[i].fw_name) {
+			log_err("fw_name is not defined. Not generating capsule GUIDs\n");
+			return EFI_INVALID_PARAMETER;
+		}
 		gen_v5_guid(&namespace,
 			    &fw_array[i].image_type_id,
 			    compatible, strlen(compatible),