From: Ramin Farajpour Cami <ramin.blackhat@gmail.com>
Date: Mon, 9 Mar 2026 16:41:45 +0000 (+0330)
Subject: [3.13] gh-145623: Fix crashes on uninitialized struct.Struct objects (gh-145624)... 
X-Git-Tag: v3.13.13~120
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b2894626aac6c44bf11f64d596f4aa52e0d5caea;p=thirdparty%2FPython%2Fcpython.git

[3.13] gh-145623: Fix crashes on uninitialized struct.Struct objects (gh-145624) (GH-145631)
---

diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index e602eeb62898..a3f8fad7a9a0 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -806,6 +806,8 @@ class StructTest(unittest.TestCase):
         self.assertRaises(RuntimeError, S.unpack, spam)
         self.assertRaises(RuntimeError, S.unpack_from, spam)
         self.assertRaises(RuntimeError, getattr, S, 'format')
+        self.assertRaises(RuntimeError, S.__sizeof__)
+        self.assertRaises(RuntimeError, repr, S)
         self.assertEqual(S.size, -1)
 
 
diff --git a/Misc/NEWS.d/next/Library/2026-03-07-15-00-00.gh-issue-145623.2Y7LzT.rst b/Misc/NEWS.d/next/Library/2026-03-07-15-00-00.gh-issue-145623.2Y7LzT.rst
new file mode 100644
index 000000000000..77b43e79e358
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-03-07-15-00-00.gh-issue-145623.2Y7LzT.rst
@@ -0,0 +1,3 @@
+Fix crash in :mod:`struct` when calling :func:`repr` or
+``__sizeof__()`` on an uninitialized :class:`struct.Struct`
+object created via ``Struct.__new__()`` without calling ``__init__()``.
diff --git a/Modules/_struct.c b/Modules/_struct.c
index 55b32f074779..c3ca125e41ab 100644
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -2196,6 +2196,7 @@ PyDoc_STRVAR(s_sizeof__doc__,
 static PyObject *
 s_sizeof(PyStructObject *self, void *unused)
 {
+    ENSURE_STRUCT_IS_READY(self);
     size_t size = _PyObject_SIZE(Py_TYPE(self)) + sizeof(formatcode);
     for (formatcode *code = self->s_codes; code->fmtdef != NULL; code++) {
         size += sizeof(formatcode);
@@ -2206,6 +2207,7 @@ s_sizeof(PyStructObject *self, void *unused)
 static PyObject *
 s_repr(PyStructObject *self)
 {
+    ENSURE_STRUCT_IS_READY(self);
     PyObject* fmt = PyUnicode_FromStringAndSize(
         PyBytes_AS_STRING(self->s_format), PyBytes_GET_SIZE(self->s_format));
     if (fmt == NULL) {