From: Neal Norwitz <nnorwitz@gmail.com>
Date: Tue, 24 Dec 2002 14:48:41 +0000 (+0000)
Subject: Fix SF #658106, Setting __class__ to NoneType
X-Git-Tag: v2.2.3c1~197
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=89b8e840726799007fd62ab4f7233ddd6662f102;p=thirdparty%2FPython%2Fcpython.git

Fix SF #658106, Setting __class__ to NoneType

Backport Guido's checkin 2.171:

Disallow class assignment completely unless both old and new are heap
types.  This prevents nonsense like 2.__class__ = bool or
True.__class__ = int.
---

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index e8ba871872ff..8b08bc0749c9 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -1702,6 +1702,13 @@ object_set_class(PyObject *self, PyObject *value, void *closure)
 		return -1;
 	}
 	new = (PyTypeObject *)value;
+	if (!(new->tp_flags & Py_TPFLAGS_HEAPTYPE) ||
+	    !(old->tp_flags & Py_TPFLAGS_HEAPTYPE))
+	{
+		PyErr_Format(PyExc_TypeError,
+			     "__class__ assignment: only for heap types");
+		return -1;
+	}
 	newbase = new;
 	oldbase = old;
 	while (equiv_structs(newbase, newbase->tp_base))
@@ -1718,13 +1725,9 @@ object_set_class(PyObject *self, PyObject *value, void *closure)
 			     old->tp_name);
 		return -1;
 	}
-	if (new->tp_flags & Py_TPFLAGS_HEAPTYPE) {
-		Py_INCREF(new);
-	}
+	Py_INCREF(new);
 	self->ob_type = new;
-	if (old->tp_flags & Py_TPFLAGS_HEAPTYPE) {
-		Py_DECREF(old);
-	}
+	Py_DECREF(old);
 	return 0;
 }