fix UBSan failures for iobase

python · encukou · Feb 8, 2025 · Jan 20, 2025 · Jan 20, 2025 · Jan 20, 2025
commit cd728f5e2ecb3ea3ada4151f7923e7f67ba0dff4
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
@@ -34,6 +34,7 @@ typedef struct {
     PyObject *dict;
     PyObject *weakreflist;
 } iobase;
+#define _iobase_CAST(op)    ((iobase *)(op))
 
 PyDoc_STRVAR(iobase_doc,
     "The abstract base class for all I/O classes.\n"
@@ -342,31 +343,34 @@ _PyIOBase_finalize(PyObject *self)
 }
 
 static int
-iobase_traverse(iobase *self, visitproc visit, void *arg)
+iobase_traverse(PyObject *op, visitproc visit, void *arg)
 {
+    iobase *self = _iobase_CAST(op);
     Py_VISIT(Py_TYPE(self));
     Py_VISIT(self->dict);
     return 0;
 }
 
 static int
-iobase_clear(iobase *self)
+iobase_clear(PyObject *op)
 {
+    iobase *self = _iobase_CAST(op);
     Py_CLEAR(self->dict);
     return 0;
 }
 
 /* Destructor */
 
 static void
-iobase_dealloc(iobase *self)
+iobase_dealloc(PyObject *self)
 {
     /* NOTE: since IOBaseObject has its own dict, Python-defined attributes
        are still available here for close() to use.
        However, if the derived class declares a __slots__, those slots are
        already gone.
     */
-    if (_PyIOBase_finalize((PyObject *) self) < 0) {
+    iobase *base = _iobase_CAST(self);
+    if (_PyIOBase_finalize(self) < 0) {
         /* When called from a heap type's dealloc, the type will be
            decref'ed on return (see e.g. subtype_dealloc in typeobject.c). */
         if (_PyType_HasFeature(Py_TYPE(self), Py_TPFLAGS_HEAPTYPE)) {
@@ -376,10 +380,10 @@ iobase_dealloc(iobase *self)
     }
     PyTypeObject *tp = Py_TYPE(self);
     _PyObject_GC_UNTRACK(self);
-    if (self->weakreflist != NULL)
-        PyObject_ClearWeakRefs((PyObject *) self);
-    Py_CLEAR(self->dict);
-    tp->tp_free((PyObject *)self);
+    if (base->weakreflist != NULL)
+        PyObject_ClearWeakRefs(self);
+    Py_CLEAR(base->dict);
+    tp->tp_free(self);
     Py_DECREF(tp);
 }
 
@@ -852,7 +856,7 @@ static PyMethodDef iobase_methods[] = {
 
 static PyGetSetDef iobase_getset[] = {
     {"__dict__", PyObject_GenericGetDict, NULL, NULL},
-    {"closed", (getter)iobase_closed_get, NULL, NULL},
+    {"closed", iobase_closed_get, NULL, NULL},
     {NULL}
 };