Fix/prevent asset graph cycles (#1179)

backend/core/serializers.py

@@ -220,6 +220,20 @@ class Meta:
         model = Asset
         fields = "__all__"
 
+    def validate_parent_assets(self, parent_assets):
+        """
+        Check that the assets graph will not contain cycles
+        """
+        if not self.instance:
+            return parent_assets
+        if parent_assets:
+            for asset in parent_assets:
+                if self.instance in asset.ancestors_plus_self():
+                    raise serializers.ValidationError(
+                        "errorAssetGraphMustNotContainCycles"
+                    )
+        return parent_assets
+
 
 class AssetReadSerializer(AssetWriteSerializer):
     folder = FieldsRelatedField()

frontend/messages/en.json

@@ -979,5 +979,6 @@
 	"attackPath": "Attack path",
 	"attackPaths": "Attack paths",
 	"currentCriticality": "Current criticality",
-	"residualCriticality": "Residual criticality"
+	"residualCriticality": "Residual criticality",
+	"errorAssetGraphMustNotContainCycles": "The asset graph must not contain cycles."
 }