bpo-31315: Fix an assertion failure in imp.create_dynamic(), when spec.name is not a string

Lib/test/test_imp.py

@@ -318,6 +318,17 @@ def test_load_source(self):
         with self.assertRaisesRegex(ValueError, 'embedded null'):
             imp.load_source(__name__, __file__ + "\0")
 
+    @support.cpython_only
+    def test_issue31315(self):
+        # There shouldn't be an assertion failure in imp.create_dynamic(),
+        # when spec.name is not a string.
+        create_dynamic = support.get_attribute(imp, 'create_dynamic')
+        class BadSpec:
+            name = None
+            origin = 'foo'
+        with self.assertRaises(TypeError):
+            create_dynamic(BadSpec())
+
 
 class ReloadTests(unittest.TestCase):
 

Misc/NEWS.d/next/Core and Builtins/2017-09-01-00-40-58.bpo-31315.ZX20bl.rst

@@ -0,0 +1,2 @@
+Fix an assertion failure in imp.create_dynamic(), when spec.name is not a
+string. Patch by Oren Milman.

Python/importdl.c

@@ -103,6 +103,11 @@ _PyImport_LoadDynamicModuleWithSpec(PyObject *spec, FILE *fp)
     if (name_unicode == NULL) {
         return NULL;
     }
+    if (!PyUnicode_Check(name_unicode)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "spec.name must be a string");
+        goto error;
+    }
 
     name = get_encoded_name(name_unicode, &hook_prefix);
     if (name == NULL) {