fix(sbom): fix error when parent of SPDX Relationships is not a packa…

…ge. (aquasecurity#6399)

pkg/sbom/core/bom.go

@@ -238,12 +238,20 @@ func (b *BOM) AddComponent(c *Component) {
 }
 
 func (b *BOM) AddRelationship(parent, child *Component, relationshipType RelationshipType) {
+	// Check the wrong parent to avoid `panic`
+	if parent == nil {
+		return
+	}
 	if parent.id == uuid.Nil {
 		b.AddComponent(parent)
 	}
 
 	if child == nil {
-		b.relationships[parent.id] = nil // Meaning no dependencies
+		// It is possible that `relationships` already contains this parent.
+		// Check this to avoid overwriting.
+		if _, ok := b.relationships[parent.id]; !ok {
+			b.relationships[parent.id] = nil // Meaning no dependencies
+		}
 		return
 	}
 

pkg/sbom/spdx/testdata/happy/with-file-as-relationship-parent.json

@@ -0,0 +1,54 @@
+{
+  "files": [
+    {
+      "fileName": "./Modules/Microsoft.PowerShell.PSResourceGet/_manifest/spdx_2.2/manifest.spdx.json",
+      "SPDXID": "SPDXRef-File--Modules-Microsoft.PowerShell.PSResourceGet--manifest-spdx-2.2-manifest.spdx.json-2B9FB98F5CA97DC84FD382A8F8E68F663C003362",
+      "checksums": [
+        {
+          "algorithm": "SHA256",
+          "checksumValue": "4201b0989938842ef8c11a006184e0b1466bd7f9bb2af61d89a4c8318d43466e"
+        },
+        {
+          "algorithm": "SHA1",
+          "checksumValue": "2b9fb98f5ca97dc84fd382a8f8e68f663c003362"
+        }
+      ],
+      "licenseConcluded": "NOASSERTION",
+      "licenseInfoInFiles": [
+        "NOASSERTION"
+      ],
+      "copyrightText": "NOASSERTION",
+      "fileTypes": [
+        "SPDX"
+      ]
+    }
+  ],
+  "externalDocumentRefs": [],
+  "relationships": [
+    {
+      "relationshipType": "DESCRIBES",
+      "relatedSpdxElement": "SPDXRef-RootPackage",
+      "spdxElementId": "SPDXRef-DOCUMENT"
+    },
+    {
+      "relationshipType": "DESCRIBED_BY",
+      "relatedSpdxElement": "SPDXRef-DOCUMENT",
+      "spdxElementId": "SPDXRef-File--Modules-Microsoft.PowerShell.PSResourceGet--manifest-spdx-2.2-manifest.spdx.json-2B9FB98F5CA97DC84FD382A8F8E68F663C003362"
+    }
+  ],
+  "spdxVersion": "SPDX-2.2",
+  "dataLicense": "CC0-1.0",
+  "SPDXID": "SPDXRef-DOCUMENT",
+  "name": "PowerShell Linux Arm32 7.5.0-preview.2",
+  "documentNamespace": "https://sbom.microsoft/1:2QSF7qZlbE-F7QrUJlEo7g:pHp_nUFvDUijZ4LrJ4RhoQ/696:458654/PowerShell%20Linux%20Arm32:7.5.0-preview.2:pDkyTHXmgUOdzSXIq9CiqA",
+  "creationInfo": {
+    "created": "2024-02-22T00:43:53Z",
+    "creators": [
+      "Organization: Microsoft",
+      "Tool: Microsoft.SBOMTool-2.2.3"
+    ]
+  },
+  "documentDescribes": [
+    "SPDXRef-RootPackage"
+  ]
+}

pkg/sbom/spdx/unmarshal.go

@@ -87,8 +87,16 @@ func (s *SPDX) unmarshal(spdxDocument *spdx.Document) error {
 			continue
 		}
 
-		compA := components[rel.RefA.ElementRefID]
-		compB := components[rel.RefB.ElementRefID]
+		compA, ok := components[rel.RefA.ElementRefID]
+		if !ok { // Skip if parent is not Package
+			continue
+		}
+
+		compB, ok := components[rel.RefB.ElementRefID]
+		if !ok { // Skip if child is not Package
+			continue
+		}
+
 		s.BOM.AddRelationship(compA, compB, s.parseRelationshipType(rel.Relationship))
 	}
 

pkg/sbom/spdx/unmarshal_test.go

@@ -314,6 +314,11 @@ func TestUnmarshaler_Unmarshal(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:      "happy path with file as parent of relationship",
+			inputFile: "testdata/happy/with-file-as-relationship-parent.json",
+			want:      types.SBOM{},
+		},
 		{
 			name:      "happy path only os component",
 			inputFile: "testdata/happy/os-only-bom.json",