C++: Exclude calls to operator new / delete from NewFreeMismatch.ql.

Author: geoffw0

cpp/ql/src/Critical/NewDelete.qll

@@ -5,6 +5,8 @@
 import cpp
 import semmle.code.cpp.controlflow.SSA
 import semmle.code.cpp.dataflow.DataFlow
+import semmle.code.cpp.models.implementations.Allocation
+import semmle.code.cpp.models.implementations.Deallocation
 
 /**
  * Holds if `alloc` is a use of `malloc` or `new`.  `kind` is
@@ -15,6 +17,7 @@ predicate allocExpr(Expr alloc, string kind) {
   not alloc.isFromUninstantiatedTemplate(_) and
   (
     alloc instanceof FunctionCall and
+    not alloc.(FunctionCall).getTarget() instanceof OperatorNewAllocationFunction and
     kind = "malloc"
     or
     alloc instanceof NewExpr and
@@ -111,6 +114,7 @@ predicate allocReaches(Expr e, Expr alloc, string kind) {
  */
 predicate freeExpr(Expr free, Expr freed, string kind) {
   freeCall(free, freed) and
+  not free.(FunctionCall).getTarget() instanceof OperatorDeleteDeallocationFunction and
   kind = "free"
   or
   free.(DeleteExpr).getExpr() = freed and

cpp/ql/test/query-tests/Critical/NewFree/NewFreeMismatch.expected

@@ -1,8 +1,6 @@
 | test2.cpp:19:3:19:6 | call to free | There is a new/free mismatch between this free and the corresponding $@. | test2.cpp:18:12:18:18 | new | new |
 | test2.cpp:26:3:26:6 | call to free | There is a new/free mismatch between this free and the corresponding $@. | test2.cpp:25:7:25:13 | new | new |
-| test2.cpp:50:2:50:18 | call to operator delete | There is a new/free mismatch between this free and the corresponding $@. | test2.cpp:45:18:45:24 | new | new |
 | test2.cpp:51:2:51:5 | call to free | There is a new/free mismatch between this free and the corresponding $@. | test2.cpp:45:18:45:24 | new | new |
-| test2.cpp:53:2:53:17 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test2.cpp:46:20:46:33 | call to operator new | malloc |
 | test2.cpp:57:2:57:18 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test2.cpp:47:21:47:26 | call to malloc | malloc |
 | test.cpp:36:2:36:17 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:27:18:27:23 | call to malloc | malloc |
 | test.cpp:41:2:41:5 | call to free | There is a new/free mismatch between this free and the corresponding $@. | test.cpp:26:7:26:17 | new | new |

cpp/ql/test/query-tests/Critical/NewFree/test2.cpp

@@ -47,10 +47,10 @@ void test_operator_new()
 	void *ptr_malloc = malloc(sizeof(int));
 
 	delete ptr_new; // GOOD
-	::operator delete(ptr_new); // GOOD [FALSE POSITIVE]
+	::operator delete(ptr_new); // GOOD
 	free(ptr_new); // BAD
 
-	delete ptr_opnew; // GOOD [FALSE POSITIVE]
+	delete ptr_opnew; // GOOD
 	::operator delete(ptr_opnew); // GOOD
 	free(ptr_opnew); // BAD [NOT DETECTED]