diff --git a/Objects/typeobject.c b/Objects/typeobject.c index 1484d9b33417b2..818a00708b5d3d 100644 --- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -2251,7 +2251,9 @@ _PyType_AllocNoTrack(PyTypeObject *type, Py_ssize_t nitems) if (PyType_IS_GC(type)) { _PyObject_GC_Link(obj); } - memset(obj, '\0', size); + // Zero out the object after the PyObject header. The header fields are + // initialized by _PyObject_Init[Var](). + memset((char *)obj + sizeof(PyObject), 0, size - sizeof(PyObject)); if (type->tp_itemsize == 0) { _PyObject_Init(obj, type); diff --git a/Python/gc.c b/Python/gc.c index 0fb2f03b0406ad..ab95a192e67a7a 100644 --- a/Python/gc.c +++ b/Python/gc.c @@ -2309,11 +2309,12 @@ PyObject * PyUnstable_Object_GC_NewWithExtraData(PyTypeObject *tp, size_t extra_size) { size_t presize = _PyType_PreHeaderSize(tp); - PyObject *op = gc_alloc(tp, _PyObject_SIZE(tp) + extra_size, presize); + size_t size = _PyObject_SIZE(tp) + extra_size; + PyObject *op = gc_alloc(tp, size, presize); if (op == NULL) { return NULL; } - memset(op, 0, _PyObject_SIZE(tp) + extra_size); + memset((char *)op + sizeof(PyObject), 0, size - sizeof(PyObject)); _PyObject_Init(op, tp); return op; } diff --git a/Python/gc_free_threading.c b/Python/gc_free_threading.c index 9e459da3a44370..1c7ff5b6650266 100644 --- a/Python/gc_free_threading.c +++ b/Python/gc_free_threading.c @@ -2593,11 +2593,12 @@ PyObject * PyUnstable_Object_GC_NewWithExtraData(PyTypeObject *tp, size_t extra_size) { size_t presize = _PyType_PreHeaderSize(tp); - PyObject *op = gc_alloc(tp, _PyObject_SIZE(tp) + extra_size, presize); + size_t size = _PyObject_SIZE(tp) + extra_size; + PyObject *op = gc_alloc(tp, size, presize); if (op == NULL) { return NULL; } - memset(op, 0, _PyObject_SIZE(tp) + extra_size); + memset((char *)op + sizeof(PyObject), 0, size - sizeof(PyObject)); _PyObject_Init(op, tp); return op; }