ACPICA: Avoid use of invalid pointers in returned object field

During operand evaluation, ensure that the ReturnObj field is
cleared on error and only valid pointers are stored there.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/executer/exoparg6.c b/drivers/acpi/executer/exoparg6.c
index bd80a9c..163b2b3 100644
--- a/drivers/acpi/executer/exoparg6.c
+++ b/drivers/acpi/executer/exoparg6.c
@@ -322,8 +322,6 @@
 		goto cleanup;
 	}
 
-	walk_state->result_obj = return_desc;
-
       cleanup:
 
 	/* Delete return object on error */
@@ -332,5 +330,11 @@
 		acpi_ut_remove_reference(return_desc);
 	}
 
+	/* Save return object on success */
+
+	else {
+		walk_state->result_obj = return_desc;
+	}
+
 	return_ACPI_STATUS(status);
 }