JS: Add: Array.protype.findLast as taint step

Author: Napalys

javascript/ql/lib/semmle/javascript/Arrays.qll

@@ -384,13 +384,16 @@ private module ArrayLibraries {
   }
 
   /**
-   * Gets a call to `Array.prototype.find` or a polyfill implementing the same functionality.
+   * Gets a call to `Array.prototype.find` or `Array.prototype.findLast` or a polyfill implementing the same functionality.
    */
   DataFlow::CallNode arrayFindCall(DataFlow::Node array) {
-    result.(DataFlow::MethodCallNode).getMethodName() = "find" and
+    result.(DataFlow::MethodCallNode).getMethodName() in ["find", "findLast"] and
     array = result.getReceiver()
     or
-    result = DataFlow::moduleImport(["array.prototype.find", "array-find"]).getACall() and
+    result =
+      DataFlow::moduleImport([
+          "array.prototype.find", "array-find", "array.prototype.findLast", "array-find-last"
+        ]).getACall() and
     array = result.getArgument(0)
   }
 

javascript/ql/test/library-tests/Arrays/DataFlow.expected

@@ -14,6 +14,7 @@
 | arrays.js:2:16:2:23 | "source" | arrays.js:90:10:90:10 | x |
 | arrays.js:2:16:2:23 | "source" | arrays.js:93:8:93:17 | arr.at(-1) |
 | arrays.js:2:16:2:23 | "source" | arrays.js:109:8:109:24 | arr8_spread.pop() |
+| arrays.js:2:16:2:23 | "source" | arrays.js:111:8:111:33 | arr.fin ... llback) |
 | arrays.js:18:22:18:29 | "source" | arrays.js:18:50:18:50 | e |
 | arrays.js:22:15:22:22 | "source" | arrays.js:23:8:23:17 | arr2.pop() |
 | arrays.js:25:15:25:22 | "source" | arrays.js:26:8:26:17 | arr3.pop() |

javascript/ql/test/library-tests/Arrays/TaintFlow.expected

@@ -15,6 +15,7 @@
 | arrays.js:2:16:2:23 | "source" | arrays.js:90:10:90:10 | x |
 | arrays.js:2:16:2:23 | "source" | arrays.js:93:8:93:17 | arr.at(-1) |
 | arrays.js:2:16:2:23 | "source" | arrays.js:109:8:109:24 | arr8_spread.pop() |
+| arrays.js:2:16:2:23 | "source" | arrays.js:111:8:111:33 | arr.fin ... llback) |
 | arrays.js:18:22:18:29 | "source" | arrays.js:18:50:18:50 | e |
 | arrays.js:22:15:22:22 | "source" | arrays.js:23:8:23:17 | arr2.pop() |
 | arrays.js:25:15:25:22 | "source" | arrays.js:26:8:26:17 | arr3.pop() |

javascript/ql/test/library-tests/Arrays/arrays.js

@@ -108,5 +108,5 @@
   arr8_spread = arr8_spread.toSpliced(0, 0, ...arr);
   sink(arr8_spread.pop()); // NOT OK
 
-  sink(arr.findLast(someCallback)); // NOT OK -- Should be flagged by the taint tracking rule, but it is not.
+  sink(arr.findLast(someCallback)); // NOT OK
 });