Issue #12973: Fix undefined-behaviour-inducing overflow check in list_repeat.
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 73624f0..36f8b9d 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -58,7 +58,7 @@
if (newsize == 0)
new_allocated = 0;
items = self->ob_item;
- if (new_allocated <= ((~(size_t)0) / sizeof(PyObject *)))
+ if (new_allocated <= (PY_SIZE_MAX / sizeof(PyObject *)))
PyMem_RESIZE(items, PyObject *, new_allocated);
else
items = NULL;
@@ -510,9 +510,9 @@
PyObject *elem;
if (n < 0)
n = 0;
- size = Py_SIZE(a) * n;
- if (n && size/n != Py_SIZE(a))
+ if (n > 0 && Py_SIZE(a) > PY_SSIZE_T_MAX / n)
return PyErr_NoMemory();
+ size = Py_SIZE(a) * n;
if (size == 0)
return PyList_New(0);
np = (PyListObject *) PyList_New(size);