From f7f9beeefdd61a3a846af84aab55fc2a202a727c Mon Sep 17 00:00:00 2001
From: Erik Krogh Kristensen <erik-krogh@github.com>
Date: Mon, 23 Nov 2020 14:23:22 +0100
Subject: [PATCH] avoid reporting empty names in `js/exposure-of-private-files`

---
 javascript/ql/src/Security/CWE-200/PrivateFileExposure.ql   | 6 +++++-
 .../Security/CWE-200/PrivateFileExposure.expected           | 1 +
 .../query-tests/Security/CWE-200/private-file-exposure.js   | 4 +++-
 .../query-tests/Security/CWE-200/subfolder/package.json     | 1 +
 .../Security/CWE-200/subfolder/private-file-exposure-2.js   | 6 ++++++
 5 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 javascript/ql/test/query-tests/Security/CWE-200/subfolder/package.json
 create mode 100644 javascript/ql/test/query-tests/Security/CWE-200/subfolder/private-file-exposure-2.js

diff --git a/javascript/ql/src/Security/CWE-200/PrivateFileExposure.ql b/javascript/ql/src/Security/CWE-200/PrivateFileExposure.ql
index 78de0c8cc18..30fbeb4dbe1 100644
--- a/javascript/ql/src/Security/CWE-200/PrivateFileExposure.ql
+++ b/javascript/ql/src/Security/CWE-200/PrivateFileExposure.ql
@@ -80,7 +80,11 @@ Folder getAPackageJSONFolder() { result = any(PackageJSON json).getFile().getPar
 DataFlow::Node getALeakingFolder(string description) {
   exists(ModuleScope ms | result.asExpr() = ms.getVariable("__dirname").getAnAccess()) and
   result.getFile().getParentContainer() = getAPackageJSONFolder() and
-  description = "the folder " + result.getFile().getParentContainer().getRelativePath()
+  (
+    if result.getFile().getParentContainer().getRelativePath().trim() != ""
+    then description = "the folder " + result.getFile().getParentContainer().getRelativePath()
+    else description = "a folder"
+  )
   or
   result = DataFlow::moduleImport("os").getAMemberCall("homedir") and
   description = "the home folder"
diff --git a/javascript/ql/test/query-tests/Security/CWE-200/PrivateFileExposure.expected b/javascript/ql/test/query-tests/Security/CWE-200/PrivateFileExposure.expected
index 9163f3fda53..ccbb8b8efd7 100644
--- a/javascript/ql/test/query-tests/Security/CWE-200/PrivateFileExposure.expected
+++ b/javascript/ql/test/query-tests/Security/CWE-200/PrivateFileExposure.expected
@@ -19,3 +19,4 @@
 | private-file-exposure.js:42:1:42:66 | app.use ... dir())) | Serves the home folder, which can contain private information. |
 | private-file-exposure.js:43:1:43:46 | app.use ... )("/")) | Serves the root folder, which can contain private information. |
 | private-file-exposure.js:51:5:51:88 | app.use ... les'))) | Serves the folder "../node_modules", which can contain private information. |
+| subfolder/private-file-exposure-2.js:6:1:6:34 | app.use ... rname)) | Serves the folder query-tests/Security/CWE-200/subfolder, which can contain private information. |
diff --git a/javascript/ql/test/query-tests/Security/CWE-200/private-file-exposure.js b/javascript/ql/test/query-tests/Security/CWE-200/private-file-exposure.js
index 2d8423e89b0..63528fd37ba 100644
--- a/javascript/ql/test/query-tests/Security/CWE-200/private-file-exposure.js
+++ b/javascript/ql/test/query-tests/Security/CWE-200/private-file-exposure.js
@@ -59,4 +59,6 @@ function good() {
 
     app.use("jquery", express.static('./node_modules/jquery/dist')); // OK
     app.use("bootstrap", express.static('./node_modules/bootstrap/dist')); // OK
-}
\ No newline at end of file
+}
+
+app.use(express.static(__dirname)) // NOT OK
\ No newline at end of file
diff --git a/javascript/ql/test/query-tests/Security/CWE-200/subfolder/package.json b/javascript/ql/test/query-tests/Security/CWE-200/subfolder/package.json
new file mode 100644
index 00000000000..9e26dfeeb6e
--- /dev/null
+++ b/javascript/ql/test/query-tests/Security/CWE-200/subfolder/package.json
@@ -0,0 +1 @@
+{}
\ No newline at end of file
diff --git a/javascript/ql/test/query-tests/Security/CWE-200/subfolder/private-file-exposure-2.js b/javascript/ql/test/query-tests/Security/CWE-200/subfolder/private-file-exposure-2.js
new file mode 100644
index 00000000000..ec2e40a7c2b
--- /dev/null
+++ b/javascript/ql/test/query-tests/Security/CWE-200/subfolder/private-file-exposure-2.js
@@ -0,0 +1,6 @@
+var express = require('express');
+var http = require('http')
+var app = express()
+var server = http.createServer(app)
+// Static files:
+app.use(express.static(__dirname))