fix UBSan failures for localobject

python · encukou · Feb 24, 2025 · Jan 25, 2025 · Jan 25, 2025 · Jan 25, 2025
commit a96a296863e74c4500d19817034d8369cc6a133f
diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
@@ -1359,6 +1359,8 @@ typedef struct {
     PyObject *thread_watchdogs;
 } localobject;
 
+#define _localobject_CAST(op)   ((localobject *)(op))
+
 /* Forward declaration */
 static int create_localsdict(localobject *self, thread_module_state *state,
                              PyObject **localsdict, PyObject **sentinel_wr);
@@ -1369,7 +1371,7 @@ static PyObject *
 create_sentinel_wr(localobject *self)
 {
     static PyMethodDef wr_callback_def = {
-        "clear_locals", (PyCFunction) clear_locals, METH_O
+        "clear_locals", clear_locals, METH_O
     };
 
     PyThreadState *tstate = PyThreadState_Get();
@@ -1461,8 +1463,9 @@ local_new(PyTypeObject *type, PyObject *args, PyObject *kw)
 }
 
 static int
-local_traverse(localobject *self, visitproc visit, void *arg)
+local_traverse(PyObject *op, visitproc visit, void *arg)
 {
+    localobject *self = _localobject_CAST(op);
     Py_VISIT(Py_TYPE(self));
     Py_VISIT(self->args);
     Py_VISIT(self->kw);
@@ -1472,8 +1475,9 @@ local_traverse(localobject *self, visitproc visit, void *arg)
 }
 
 static int
-local_clear(localobject *self)
+local_clear(PyObject *op)
 {
+    localobject *self = _localobject_CAST(op);
     Py_CLEAR(self->args);
     Py_CLEAR(self->kw);
     Py_CLEAR(self->localdicts);
@@ -1482,20 +1486,18 @@ local_clear(localobject *self)
 }
 
 static void
-local_dealloc(localobject *self)
+local_dealloc(PyObject *op)
 {
+    localobject *self = _localobject_CAST(op);
     /* Weakrefs must be invalidated right now, otherwise they can be used
        from code called below, which is very dangerous since Py_REFCNT(self) == 0 */
     if (self->weakreflist != NULL) {
-        PyObject_ClearWeakRefs((PyObject *) self);
+        PyObject_ClearWeakRefs(op);
     }
-
     PyObject_GC_UnTrack(self);
-
-    local_clear(self);
-
+    (void)local_clear(op);
     PyTypeObject *tp = Py_TYPE(self);
-    tp->tp_free((PyObject*)self);
+    tp->tp_free(self);
     Py_DECREF(tp);
 }
 
@@ -1634,8 +1636,9 @@ _ldict(localobject *self, thread_module_state *state)
 }
 
 static int
-local_setattro(localobject *self, PyObject *name, PyObject *v)
+local_setattro(PyObject *op, PyObject *name, PyObject *v)
 {
+    localobject *self = _localobject_CAST(op);
     PyObject *module = PyType_GetModuleByDef(Py_TYPE(self), &thread_module);
     assert(module != NULL);
     thread_module_state *state = get_thread_state(module);
@@ -1656,8 +1659,7 @@ local_setattro(localobject *self, PyObject *name, PyObject *v)
         goto err;
     }
 
-    int st =
-        _PyObject_GenericSetAttrWithDict((PyObject *)self, name, v, ldict);
+    int st = _PyObject_GenericSetAttrWithDict(op, name, v, ldict);
     Py_DECREF(ldict);
     return st;
 
@@ -1666,20 +1668,20 @@ local_setattro(localobject *self, PyObject *name, PyObject *v)
     return -1;
 }
 
-static PyObject *local_getattro(localobject *, PyObject *);
+static PyObject *local_getattro(PyObject *, PyObject *);
 
 static PyMemberDef local_type_members[] = {
     {"__weaklistoffset__", Py_T_PYSSIZET, offsetof(localobject, weakreflist), Py_READONLY},
     {NULL},
 };
 
 static PyType_Slot local_type_slots[] = {
-    {Py_tp_dealloc, (destructor)local_dealloc},
-    {Py_tp_getattro, (getattrofunc)local_getattro},
-    {Py_tp_setattro, (setattrofunc)local_setattro},
+    {Py_tp_dealloc, local_dealloc},
+    {Py_tp_getattro, local_getattro},
+    {Py_tp_setattro, local_setattro},
     {Py_tp_doc, "_local()\n--\n\nThread-local data"},
-    {Py_tp_traverse, (traverseproc)local_traverse},
-    {Py_tp_clear, (inquiry)local_clear},
+    {Py_tp_traverse, local_traverse},
+    {Py_tp_clear, local_clear},
     {Py_tp_new, local_new},
     {Py_tp_members, local_type_members},
     {0, 0}
@@ -1694,8 +1696,9 @@ static PyType_Spec local_type_spec = {
 };
 
 static PyObject *
-local_getattro(localobject *self, PyObject *name)
+local_getattro(PyObject *op, PyObject *name)
 {
+    localobject *self = _localobject_CAST(op);
     PyObject *module = PyType_GetModuleByDef(Py_TYPE(self), &thread_module);
     assert(module != NULL);
     thread_module_state *state = get_thread_state(module);
@@ -1715,8 +1718,7 @@ local_getattro(localobject *self, PyObject *name)
 
     if (!Py_IS_TYPE(self, state->local_type)) {
         /* use generic lookup for subtypes */
-        PyObject *res =
-            _PyObject_GenericGetAttrWithDict((PyObject *)self, name, ldict, 0);
+        PyObject *res = _PyObject_GenericGetAttrWithDict(op, name, ldict, 0);
         Py_DECREF(ldict);
         return res;
     }
@@ -1730,8 +1732,7 @@ local_getattro(localobject *self, PyObject *name)
     }
 
     /* Fall back on generic to get __class__ and __dict__ */
-    PyObject *res =
-        _PyObject_GenericGetAttrWithDict((PyObject *)self, name, ldict, 0);
+    PyObject *res = _PyObject_GenericGetAttrWithDict(op, name, ldict, 0);
     Py_DECREF(ldict);
     return res;
 }