C++: Exclude results where the address of the variable is taken.

Author: geoffw0

cpp/ql/src/Likely Bugs/Memory Management/ImproperNullTermination.ql

@@ -53,6 +53,7 @@ class ImproperNullTerminationReachability extends StackVariableReachabilityWithR
   override predicate isBarrier(ControlFlowNode node, StackVariable v) {
     exprDefinition(v, node, _) or
     mayAddNullTerminator(node, v.getAnAccess()) or
+    node.(AddressOfExpr).getOperand() = v.getAnAccess() or // address taken
     isSinkActual(node, v) // only report first use
   }
 }

cpp/ql/test/query-tests/Likely Bugs/Memory Management/ImproperNullTermination/ImproperNullTermination.expected

@@ -26,4 +26,3 @@
 | test.cpp:421:19:421:25 | buffer2 | Variable $@ may not be null terminated. | test.cpp:419:8:419:14 | buffer2 | buffer2 |
 | test.cpp:448:17:448:22 | buffer | Variable $@ may not be null terminated. | test.cpp:446:8:446:13 | buffer | buffer |
 | test.cpp:454:18:454:23 | buffer | Variable $@ may not be null terminated. | test.cpp:452:8:452:13 | buffer | buffer |
-| test.cpp:502:10:502:18 | after_ptr | Variable $@ may not be null terminated. | test.cpp:497:9:497:17 | after_ptr | after_ptr |

cpp/ql/test/query-tests/Likely Bugs/Memory Management/ImproperNullTermination/test.cpp

@@ -499,6 +499,6 @@ void test_strtol()
 
 		strcpy(buffer, "123abc");
 		num = strtol("123abc", &after_ptr, 10);
-		strlen(after_ptr); // GOOD [FALSE POSITIVE]
+		strlen(after_ptr); // GOOD
 	}
 }