Bug fix for access path handling (#1001)

Author: fabsx00

dataflowengineoss/src/main/scala/io/shiftleft/dataflowengineoss/passes/reachingdef/UsageAnalyzer.scala

@@ -2,7 +2,7 @@ package io.shiftleft.dataflowengineoss.passes.reachingdef
 
 import io.shiftleft.codepropertygraph.generated.nodes
 import io.shiftleft.codepropertygraph.generated.nodes.StoredNode
-import io.shiftleft.semanticcpg.accesspath.{MatchResult}
+import io.shiftleft.semanticcpg.accesspath.MatchResult
 import io.shiftleft.semanticcpg.language.nodemethods.TrackingPointMethodsBase.ImplicitsAPI
 import io.shiftleft.semanticcpg.language._
 import overflowdb.traversal._
@@ -32,7 +32,7 @@ class UsageAnalyzer(in: Map[nodes.StoredNode, Set[Definition]]) {
         val (matchResult, elements) = useAccessPath.matchAndDiff(defAccessPath.elements)
         (useBase == inBase) && // filter *x -> x
         !(matchResult == MatchResult.EXTENDED_MATCH && elements.elements.length > 1 && elements.elements.headOption
-          .exists(_.toString == "*"))
+          .exists(_.toString == "*")) && matchResult != MatchResult.NO_MATCH
       case _ => false
     }
   }

dataflowengineoss/src/test/scala/io/shiftleft/dataflowengineoss/language/CDataFlowTests.scala

@@ -1,6 +1,8 @@
 package io.shiftleft.dataflowengineoss.language
 
+import io.shiftleft.dataflowengineoss.semanticsloader.Semantics
 import io.shiftleft.semanticcpg.language._
+import overflowdb.traversal.Traversal
 
 class CDataFlowTests1 extends DataFlowCodeToCpgSuite {
 
@@ -801,3 +803,29 @@ class CDataFlowTests23 extends DataFlowCodeToCpgSuite {
   }
 
 }
+
+class CDataFlowTests24 extends DataFlowCodeToCpgSuite {
+  override val code =
+    """
+      |int foo() {
+      |  source(&a->c);
+      |  sink(a->b);
+      |}
+      |
+      |int bar() {
+      |  source(&a->b);
+      |  sink(a->b);
+      |}
+      |
+      |""".stripMargin
+
+  "Test 24: should not report flow if access path differs" in {
+    val source = cpg.call.name("source").argument.l
+    val sink = cpg.method.name("sink").parameter.l
+    implicit val s: Semantics = semantics
+    val flows = sink.to(Traversal).reachableByFlows(source.to(Traversal)).l
+    flows.map(flowToResultPairs).toSet shouldBe Set(
+      List(("source(&a->b)", Some(8)), ("sink(a->b)", Some(9)), ("sink(p1)", None)))
+  }
+
+}