bpo-30746: Prohibited the '=' character in environment variable names (#2382)

in `os.putenv()` and `os.spawn*()`.

Lib/test/test_os.py

@@ -2382,6 +2382,55 @@ class SpawnTests(unittest.TestCase):
         self.assertRaises(ValueError, os.spawnve, os.P_NOWAIT, args[0], ('',), {})
         self.assertRaises(ValueError, os.spawnve, os.P_NOWAIT, args[0], [''], {})
 
+    @requires_os_func('spawnve')
+    def test_spawnve_invalid_env(self):
+        # null character in the enviroment variable name
+        args = [sys.executable, '-c', 'pass']
+        newenv = os.environ.copy()
+        newenv["FRUIT\0VEGETABLE"] = "cabbage"
+        try:
+            exitcode = os.spawnve(os.P_WAIT, args[0], args, newenv)
+        except ValueError:
+            pass
+        else:
+            self.assertEqual(exitcode, 127)
+
+        # null character in the enviroment variable value
+        args = [sys.executable, '-c', 'pass']
+        newenv = os.environ.copy()
+        newenv["FRUIT"] = "orange\0VEGETABLE=cabbage"
+        try:
+            exitcode = os.spawnve(os.P_WAIT, args[0], args, newenv)
+        except ValueError:
+            pass
+        else:
+            self.assertEqual(exitcode, 127)
+
+        # equal character in the enviroment variable name
+        args = [sys.executable, '-c', 'pass']
+        newenv = os.environ.copy()
+        newenv["FRUIT=ORANGE"] = "lemon"
+        try:
+            exitcode = os.spawnve(os.P_WAIT, args[0], args, newenv)
+        except ValueError:
+            pass
+        else:
+            self.assertEqual(exitcode, 127)
+
+        # equal character in the enviroment variable value
+        filename = support.TESTFN
+        self.addCleanup(support.unlink, filename)
+        with open(filename, "w") as fp:
+            fp.write('import sys, os\n'
+                     'if os.getenv("FRUIT") != "orange=lemon":\n'
+                     '    raise AssertionError')
+        args = [sys.executable, filename]
+        newenv = os.environ.copy()
+        newenv["FRUIT"] = "orange=lemon"
+        exitcode = os.spawnve(os.P_WAIT, args[0], args, newenv)
+        self.assertEqual(exitcode, 0)
+
+
 # The introduction of this TestCase caused at least two different errors on
 # *nix buildbots. Temporarily skip this to let the buildbots move along.
 @unittest.skip("Skip due to platform/environment differences on *NIX buildbots")

Lib/test/test_posix.py

@@ -813,6 +813,21 @@ class PosixTester(unittest.TestCase):
             self.assertEqual(type(k), item_type)
             self.assertEqual(type(v), item_type)
 
+    @unittest.skipUnless(hasattr(os, "putenv"), "requires os.putenv()")
+    def test_putenv(self):
+        with self.assertRaises(ValueError):
+            os.putenv('FRUIT\0VEGETABLE', 'cabbage')
+        with self.assertRaises(ValueError):
+            os.putenv(b'FRUIT\0VEGETABLE', b'cabbage')
+        with self.assertRaises(ValueError):
+            os.putenv('FRUIT', 'orange\0VEGETABLE=cabbage')
+        with self.assertRaises(ValueError):
+            os.putenv(b'FRUIT', b'orange\0VEGETABLE=cabbage')
+        with self.assertRaises(ValueError):
+            os.putenv('FRUIT=ORANGE', 'lemon')
+        with self.assertRaises(ValueError):
+            os.putenv(b'FRUIT=ORANGE', b'lemon')
+
     @unittest.skipUnless(hasattr(posix, 'getcwd'), 'test needs posix.getcwd()')
     def test_getcwd_long_pathnames(self):
         dirname = 'getcwd-test-directory-0123456789abcdef-01234567890abcdef'

Misc/NEWS

@@ -374,6 +374,9 @@ Extension Modules
 Library
 -------
 
+- bpo-30746: Prohibited the '=' character in environment variable names in
+  ``os.putenv()`` and ``os.spawn*()``.
+
 - bpo-30664: The description of a unittest subtest now preserves the order of
   keyword arguments of TestCase.subTest().
 

Modules/posixmodule.c

@@ -4894,6 +4894,14 @@ parse_envlist(PyObject* env, Py_ssize_t *envc_ptr)
             Py_DECREF(key2);
             goto error;
         }
+        /* Search from index 1 because on Windows starting '=' is allowed for
+           defining hidden environment variables. */
+        if (PyUnicode_GET_LENGTH(key2) == 0 ||
+            PyUnicode_FindChar(key2, '=', 1, PyUnicode_GET_LENGTH(key2), 1) != -1)
+        {
+            PyErr_SetString(PyExc_ValueError, "illegal environment variable name");
+            goto error;
+        }
         keyval = PyUnicode_FromFormat("%U=%U", key2, val2);
 #else
         if (!PyUnicode_FSConverter(key, &key2))
@@ -4902,6 +4910,12 @@ parse_envlist(PyObject* env, Py_ssize_t *envc_ptr)
             Py_DECREF(key2);
             goto error;
         }
+        if (PyBytes_GET_SIZE(key2) == 0 ||
+            strchr(PyBytes_AS_STRING(key2) + 1, '=') != NULL)
+        {
+            PyErr_SetString(PyExc_ValueError, "illegal environment variable name");
+            goto error;
+        }
         keyval = PyBytes_FromFormat("%s=%s", PyBytes_AS_STRING(key2),
                                              PyBytes_AS_STRING(val2));
 #endif
@@ -8985,9 +8999,16 @@ os_putenv_impl(PyObject *module, PyObject *name, PyObject *value)
 {
     const wchar_t *env;
 
+    /* Search from index 1 because on Windows starting '=' is allowed for
+       defining hidden environment variables. */
+    if (PyUnicode_GET_LENGTH(name) == 0 ||
+        PyUnicode_FindChar(name, '=', 1, PyUnicode_GET_LENGTH(name), 1) != -1)
+    {
+        PyErr_SetString(PyExc_ValueError, "illegal environment variable name");
+        return NULL;
+    }
     PyObject *unicode = PyUnicode_FromFormat("%U=%U", name, value);
     if (unicode == NULL) {
-        PyErr_NoMemory();
         return NULL;
     }
     if (_MAX_ENV < PyUnicode_GET_LENGTH(unicode)) {
@@ -9029,12 +9050,15 @@ os_putenv_impl(PyObject *module, PyObject *name, PyObject *value)
 {
     PyObject *bytes = NULL;
     char *env;
-    const char *name_string = PyBytes_AsString(name);
-    const char *value_string = PyBytes_AsString(value);
+    const char *name_string = PyBytes_AS_STRING(name);
+    const char *value_string = PyBytes_AS_STRING(value);
 
+    if (strchr(name_string, '=') != NULL) {
+        PyErr_SetString(PyExc_ValueError, "illegal environment variable name");
+        return NULL;
+    }
     bytes = PyBytes_FromFormat("%s=%s", name_string, value_string);
     if (bytes == NULL) {
-        PyErr_NoMemory();
         return NULL;
     }