[Python-checkins] bpo-44707: Fix an undefined behavior of the null pointer arithmetic (GH-27292)
markshannon
webhook-mailer at python.org
Thu Jul 29 07:36:32 EDT 2021
https://github.com/python/cpython/commit/e5c8ddb1714fb51ab1defa24352c98e0f01205dc
commit: e5c8ddb1714fb51ab1defa24352c98e0f01205dc
branch: main
author: Serhiy Storchaka <storchaka at gmail.com>
committer: markshannon <mark at hotpy.org>
date: 2021-07-29T12:36:24+01:00
summary:
bpo-44707: Fix an undefined behavior of the null pointer arithmetic (GH-27292)
files:
M Objects/listobject.c
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 6eb7dce759cf8..898cbc20c5f81 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -180,9 +180,10 @@ PyList_New(Py_ssize_t size)
static PyObject *
list_new_prealloc(Py_ssize_t size)
{
+ assert(size > 0);
PyListObject *op = (PyListObject *) PyList_New(0);
- if (size == 0 || op == NULL) {
- return (PyObject *) op;
+ if (op == NULL) {
+ return NULL;
}
assert(op->ob_item == NULL);
op->ob_item = PyMem_New(PyObject *, size);
@@ -459,6 +460,9 @@ list_slice(PyListObject *a, Py_ssize_t ilow, Py_ssize_t ihigh)
PyObject **src, **dest;
Py_ssize_t i, len;
len = ihigh - ilow;
+ if (len <= 0) {
+ return PyList_New(0);
+ }
np = (PyListObject *) list_new_prealloc(len);
if (np == NULL)
return NULL;
@@ -512,6 +516,9 @@ list_concat(PyListObject *a, PyObject *bb)
#define b ((PyListObject *)bb)
assert((size_t)Py_SIZE(a) + (size_t)Py_SIZE(b) < PY_SSIZE_T_MAX);
size = Py_SIZE(a) + Py_SIZE(b);
+ if (size == 0) {
+ return PyList_New(0);
+ }
np = (PyListObject *) list_new_prealloc(size);
if (np == NULL) {
return NULL;
More information about the Python-checkins
mailing list