bpo-25794: Fix `type.__setattr__()` for non-interned attribute names. (#1652)

Based on patch by Eryk Sun.

1 files changed, 33 insertions, 6 deletions

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 121d66d..224fe61 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -3138,10 +3138,35 @@ type_setattro(PyTypeObject *type, PyObject *name, PyObject *value)
             type->tp_name);
         return -1;
     }
-    if (_PyObject_GenericSetAttrWithDict((PyObject *)type, name, value, NULL) < 0)
-        return -1;
-    res = update_slot(type, name);
-    assert(_PyType_CheckConsistency(type));
+    if (PyUnicode_Check(name)) {
+        if (PyUnicode_CheckExact(name)) {
+            if (PyUnicode_READY(name) == -1)
+                return -1;
+            Py_INCREF(name);
+        }
+        else {
+            name = _PyUnicode_Copy(name);
+            if (name == NULL)
+                return -1;
+        }
+        PyUnicode_InternInPlace(&name);
+        if (!PyUnicode_CHECK_INTERNED(name)) {
+            PyErr_SetString(PyExc_MemoryError,
+                            "Out of memory interning an attribute name");
+            Py_DECREF(name);
+            return -1;
+        }
+    }
+    else {
+        /* Will fail in _PyObject_GenericSetAttrWithDict. */
+        Py_INCREF(name);
+    }
+    res = _PyObject_GenericSetAttrWithDict((PyObject *)type, name, value, NULL);
+    if (res == 0) {
+        res = update_slot(type, name);
+        assert(_PyType_CheckConsistency(type));
+    }
+    Py_DECREF(name);
     return res;
 }
 
@@ -7065,7 +7090,7 @@ init_slotdefs(void)
         /* Slots must be ordered by their offset in the PyHeapTypeObject. */
         assert(!p[1].name || p->offset <= p[1].offset);
         p->name_strobj = PyUnicode_InternFromString(p->name);
-        if (!p->name_strobj)
+        if (!p->name_strobj || !PyUnicode_CHECK_INTERNED(p->name_strobj))
             Py_FatalError("Out of memory interning slotdef names");
     }
     slotdefs_initialized = 1;
@@ -7090,6 +7115,9 @@ update_slot(PyTypeObject *type, PyObject *name)
     slotdef **pp;
     int offset;
 
+    assert(PyUnicode_CheckExact(name));
+    assert(PyUnicode_CHECK_INTERNED(name));
+
     /* Clear the VALID_VERSION flag of 'type' and all its
        subclasses.  This could possibly be unified with the
        update_subclasses() recursion below, but carefully:
@@ -7100,7 +7128,6 @@ update_slot(PyTypeObject *type, PyObject *name)
     init_slotdefs();
     pp = ptrs;
     for (p = slotdefs; p->name; p++) {
-        /* XXX assume name is interned! */
         if (p->name_strobj == name)
             *pp++ = p;
     }