bpo-32137: The repr of deeply nested dict now raises a RecursionError (#4570)

instead of crashing due to a stack overflow.

This perhaps will fix similar problems in other extension types.

3 files changed, 5 insertions, 6 deletions

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 8576b7a..8794e37 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -364,10 +364,7 @@ list_repr(PyListObject *v)
                 goto error;
         }
 
-        if (Py_EnterRecursiveCall(" while getting the repr of a list"))
-            goto error;
         s = PyObject_Repr(v->ob_item[i]);
-        Py_LeaveRecursiveCall();
         if (s == NULL)
             goto error;
 
diff --git a/Objects/object.c b/Objects/object.c
index 674180d..a0d651d 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -463,7 +463,12 @@ PyObject_Repr(PyObject *v)
     assert(!PyErr_Occurred());
 #endif
 
+    /* It is possible for a type to have a tp_repr representation that loops
+       infinitely. */
+    if (Py_EnterRecursiveCall(" while getting the repr of an object"))
+        return NULL;
     res = (*v->ob_type->tp_repr)(v);
+    Py_LeaveRecursiveCall();
     if (res == NULL)
         return NULL;
     if (!PyUnicode_Check(res)) {
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 964db3b..3a60946 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -303,10 +303,7 @@ tuplerepr(PyTupleObject *v)
                 goto error;
         }
 
-        if (Py_EnterRecursiveCall(" while getting the repr of a tuple"))
-            goto error;
         s = PyObject_Repr(v->ob_item[i]);
-        Py_LeaveRecursiveCall();
         if (s == NULL)
             goto error;