Also make __class_getitem__ safer

ilevkivskyi · ilevkivskyi · commit e858ea7501b6 · 2017-11-11T10:01:20.000+01:00
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
@@ -3492,13 +3492,18 @@ static PyObject *
 generic_subscript(PyTypeObject *tp, PyObject *key)
 {
     PyObject* stack[2] = {(PyObject *)tp, key};
-    PyObject *meth = PyObject_GetAttrString((PyObject *)tp, "__class_getitem__");
     const char* msg = "'%.200s' object is not subscriptable";
-    if (meth){
+    PyObject *meth = PyObject_GetAttrString((PyObject *)tp, "__class_getitem__");
+    if (meth) {
+        if (!PyCallable_Check(meth)) {
+            PyErr_SetString(PyExc_TypeError,
+                            "__class_getitem__ must be callable");
+            return NULL;
+        }
         return _PyObject_FastCall(meth, stack, 2);
     }
-    else{
-        if (PyErr_ExceptionMatches(PyExc_AttributeError)){
+    else {
+        if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
             PyErr_Clear();
             PyErr_Format(PyExc_TypeError, msg, ((PyObject *)tp)->ob_type->tp_name);
             return NULL;
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
@@ -53,7 +53,7 @@ update_bases(PyObject* bases, PyObject** args, int nargs, int* modified_bases)
     PyObject *new_bases;
     assert(PyTuple_Check(bases));
 
-    /* We have a separate cycle to calculate replacements with the idea that
+    /* We have a separate cycle to calculate replacements with the idea that in
        most cases we just scroll quickly though it and return original bases */
     for (i = 2; i < nargs; i++){
         PyObject *base, *new_base, *new_base_meth;
@@ -73,9 +73,8 @@ update_bases(PyObject* bases, PyObject** args, int nargs, int* modified_bases)
         }
         else {
             if (!PyCallable_Check(new_base_meth)) {
-                PyErr_Format(PyExc_TypeError,
-                             "attribute of type '%.200s' is not callable",
-                             Py_TYPE(new_base_meth)->tp_name);
+                PyErr_SetString(PyExc_TypeError,
+                                "__base_subclass__ must be callable");
                 return NULL;
             }
             stack[0] = bases;
