Merge pull request #17965 from Napalys/napalys/immutable-array-operations

JS: Added support for toSorted and toReversed

Author: Napalys

javascript/ql/lib/change-notes/2024-11-12-immutable-array-operations.md

@@ -0,0 +1,5 @@
+---
+category: minorAnalysis
+---
+* Added taint-steps for `Array.prototype.toReversed`.
+* Added taint-steps for `Array.prototype.toSorted`.

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

@@ -458,4 +458,18 @@ private module ArrayLibraries {
       )
     }
   }
+
+  /**
+   * A taint propagating data flow edge arising from array transformation operations
+   * that return a new array instead of modifying the original array in place.
+   */
+  private class ImmutableArrayTransformStep extends TaintTracking::SharedTaintStep {
+    override predicate heapStep(DataFlow::Node pred, DataFlow::Node succ) {
+      exists(DataFlow::MethodCallNode call |
+        call.getMethodName() in ["toSorted", "toReversed"] and
+        pred = call.getReceiver() and
+        succ = call
+      )
+    }
+  }
 }

javascript/ql/test/library-tests/TaintTracking/BasicTaintTracking.expected

@@ -234,6 +234,10 @@ typeInferenceMismatch
 | tst.js:2:13:2:20 | source() | tst.js:51:10:51:31 | seriali ... ript(x) |
 | tst.js:2:13:2:20 | source() | tst.js:54:14:54:19 | unsafe |
 | tst.js:2:13:2:20 | source() | tst.js:61:10:61:20 | x.reverse() |
+| tst.js:2:13:2:20 | source() | tst.js:63:10:63:21 | x.toSorted() |
+| tst.js:2:13:2:20 | source() | tst.js:65:10:65:16 | xSorted |
+| tst.js:2:13:2:20 | source() | tst.js:67:10:67:23 | x.toReversed() |
+| tst.js:2:13:2:20 | source() | tst.js:69:10:69:18 | xReversed |
 | xml.js:5:18:5:25 | source() | xml.js:8:14:8:17 | text |
 | xml.js:12:17:12:24 | source() | xml.js:13:14:13:19 | result |
 | xml.js:23:18:23:25 | source() | xml.js:20:14:20:17 | attr |

javascript/ql/test/library-tests/TaintTracking/tst.js

@@ -59,4 +59,12 @@ function test() {
     tagged`foo ${"safe"} bar ${x} baz`;
 
     sink(x.reverse()); // NOT OK
+
+    sink(x.toSorted()) // NOT OK
+    const xSorted = x.toSorted();
+    sink(xSorted) // NOT OK
+
+    sink(x.toReversed()) // NOT OK
+    const xReversed = x.toReversed();
+    sink(xReversed) // NOT OK
 }