add support for the fast-json-stringify library

Author: erik-krogh

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

@@ -10,4 +10,5 @@ lgtm,codescanning
     [safe-stable-stringify](https://npmjs.com/package/safe-stable-stringify),
     [fclone](https://npmjs.com/package/fclone),
     [json-cycle](https://npmjs.com/package/json-cycle),
-    [strip-json-comments](https://npmjs.com/package/strip-json-comments)
+    [strip-json-comments](https://npmjs.com/package/strip-json-comments),
+    [fast-json-stringify](https://npmjs.com/package/fast-json-stringify)

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

@@ -19,7 +19,7 @@ class JsonStringifyCall extends DataFlow::CallNode {
         DataFlow::moduleImport([
             "json-stringify-safe", "json-stable-stringify", "stringify-object",
             "fast-json-stable-stringify", "fast-safe-stringify", "javascript-stringify",
-            "js-stringify", "safe-stable-stringify"
+            "js-stringify", "safe-stable-stringify", "fast-json-stringify"
           ]) or
       // require("util").inspect() and similar
       callee = DataFlow::moduleMember("util", "inspect") or

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

@@ -98,6 +98,7 @@ typeInferenceMismatch
 | json-stringify.js:2:16:2:23 | source() | json-stringify.js:36:8:36:47 | require ... source) |
 | json-stringify.js:2:16:2:23 | source() | json-stringify.js:39:8:39:37 | jc.stri ... ource)) |
 | json-stringify.js:2:16:2:23 | source() | json-stringify.js:42:8:42:51 | JSON.st ... urce))) |
+| json-stringify.js:2:16:2:23 | source() | json-stringify.js:45:8:45:23 | fastJson(source) |
 | 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

@@ -40,4 +40,7 @@ function foo() {
 
   const stripper = require("strip-json-comments");
   sink(JSON.stringify(JSON.parse(stripper(source)))); // NOT OK
+
+  const fastJson = require('fast-json-stringify');
+  sink(fastJson(source)); // NOT OK
 }