Index: Objects/object.c
===================================================================
--- Objects/object.c	(revision 57711)
+++ Objects/object.c	(working copy)
@@ -359,7 +359,11 @@
 					   Py_Type(v)->tp_name, v);
 	else {
 		PyObject *res;
+        if (Py_EnterRecursiveCall(" in repr")) {
+            return NULL;
+        }
 		res = (*Py_Type(v)->tp_repr)(v);
+	    Py_LeaveRecursiveCall();
 		if (res == NULL)
 			return NULL;
 #ifdef Py_USING_UNICODE
@@ -424,7 +428,11 @@
 PyObject *
 PyObject_Str(PyObject *v)
 {
+    if (Py_EnterRecursiveCall(" in str")) {
+        return NULL;
+    }
 	PyObject *res = _PyObject_Str(v);
+	Py_LeaveRecursiveCall();
 	if (res == NULL)
 		return NULL;
 #ifdef Py_USING_UNICODE
Index: Lib/test/test_exceptions.py
===================================================================
--- Lib/test/test_exceptions.py	(revision 57711)
+++ Lib/test/test_exceptions.py	(working copy)
@@ -343,6 +343,13 @@
         self.failUnless(str(Exception('a')))
         self.failUnless(unicode(Exception(u'a')))
 
+    def testStrReprInfiniteRecursion(self):
+        class A(Exception):
+            def __init__(self):
+                Exception.__init__(self, self)
+        a = A()
+        self.assertRaises(RuntimeError, str, a)
+        self.assertRaises(RuntimeError, repr, a)
 
 def test_main():
     run_unittest(ExceptionTests)