Create IfStatementAdditionOverflow.ql

Author: nmouha

cpp/ql/src/experimental/Security/CWE/CWE-190/IfStatementAdditionOverflow.ql

@@ -0,0 +1,28 @@
+/**
+ * @name Integer addition may overflow inside if statement
+ * @description Detects "if (a+b>c) a=c-b", which is incorrect if a+b overflows.
+ *              Should be replaced by "if (a>c-b) a=c-b", which correctly
+ *              implements a = min(a,c-b)". This integer overflow is the root
+ *              cause of the buffer overflow in the SHA-3 reference implementation
+ *              (CVE-2022-37454).
+ * @kind problem
+ * @problem.severity warning
+ * @id cpp/if-statement-addition-overflow
+ * @tags: experimental
+ *        correctness
+ *        security
+ *        external/cwe/cwe-190
+ */
+
+import cpp
+
+from IfStmt ifstmt, GTExpr gtexpr, ExprStmt exprstmt, AssignExpr assignexpr, AddExpr addexpr, SubExpr subexpr
+where ifstmt.getCondition() = gtexpr and
+  gtexpr.getLeftOperand() = addexpr and
+  ifstmt.getThen() = exprstmt and
+  exprstmt.getExpr() = assignexpr and
+  assignexpr.getRValue() = subexpr and
+  addexpr.getLeftOperand().toString() = assignexpr.getLValue().toString() and
+  addexpr.getRightOperand().toString() = subexpr.getRightOperand().toString() and
+  gtexpr.getRightOperand().toString() = subexpr.getLeftOperand().toString()
+select ifstmt, "Integer addition may overflow inside if statement."