add support for the flatted library

Author: erik-krogh

javascript/change-notes/2021-06-24-json.md

@@ -3,4 +3,5 @@ lgtm,codescanning
   Affected packages are
     [json2csv](https://npmjs.com/package/json2csv),
     [json5](https://npmjs.com/package/json5),
-    [prettyjson](https://npmjs.com/package/prettyjson)
+    [prettyjson](https://npmjs.com/package/prettyjson),
+    [flatted](https://npmjs.com/package/flatted)

javascript/ql/src/semmle/javascript/JsonParsers.qll

@@ -26,7 +26,7 @@ private class PlainJsonParserCall extends JsonParserCall {
   PlainJsonParserCall() {
     exists(DataFlow::SourceNode callee | this = callee.getACall() |
       callee = DataFlow::globalVarRef("JSON").getAPropertyRead("parse") or
-      callee = DataFlow::moduleMember(["json3", "json5"], "parse") or
+      callee = DataFlow::moduleMember(["json3", "json5", "flatted"], "parse") or
       callee = DataFlow::moduleImport("parse-json") or
       callee = DataFlow::moduleImport("json-parse-better-errors") or
       callee = DataFlow::moduleImport("json-safe-parse") or

javascript/ql/src/semmle/javascript/JsonStringifiers.qll

@@ -11,7 +11,7 @@ class JsonStringifyCall extends DataFlow::CallNode {
   JsonStringifyCall() {
     exists(DataFlow::SourceNode callee | this = callee.getACall() |
       callee = DataFlow::globalVarRef("JSON").getAPropertyRead("stringify") or
-      callee = DataFlow::moduleMember(["json3", "json5"], "stringify") or
+      callee = DataFlow::moduleMember(["json3", "json5", "flatted"], "stringify") or
       callee =
         DataFlow::moduleImport([
             "json-stringify-safe", "json-stable-stringify", "stringify-object",

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

@@ -92,6 +92,7 @@ typeInferenceMismatch
 | json-stringify.js:2:16:2:23 | source() | json-stringify.js:18:8:18:40 | require ... source) |
 | json-stringify.js:2:16:2:23 | source() | json-stringify.js:21:8:21:46 | new jso ... source) |
 | json-stringify.js:2:16:2:23 | source() | json-stringify.js:24:8:24:43 | json5.s ... ource)) |
+| json-stringify.js:2:16:2:23 | source() | json-stringify.js:27:8:27:47 | flatted ... ource)) |
 | json-stringify.js:3:15:3:22 | source() | json-stringify.js:8:8:8:31 | jsonStr ... (taint) |
 | nested-props.js:4:13:4:20 | source() | nested-props.js:5:10:5:14 | obj.x |
 | nested-props.js:9:18:9:25 | source() | nested-props.js:10:10:10:16 | obj.x.y |

javascript/ql/test/library-tests/TaintTracking/json-stringify.js

@@ -22,4 +22,7 @@ function foo() {
 
   const json5 = require('json5');
   sink(json5.stringify(json5.parse(source))); // NOT OK
+
+  const flatted = require('flatted');
+  sink(flatted.stringify(flatted.parse(source))); // NOT OK
 }