From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Tue, 19 May 2026 04:41:43 +0000 (+0200)
Subject: [3.15] gh-149816: fix thread safety of deletion of list slice (GH-149936) (#150003)
X-Git-Tag: v3.15.0b2~127
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=0b92f01c59c82a111bb6b9929fbfc0f9cb1241db;p=thirdparty%2FPython%2Fcpython.git

[3.15] gh-149816: fix thread safety of deletion of list slice (GH-149936) (#150003)

gh-149816: fix thread safety of deletion of list slice (GH-149936)
(cherry picked from commit 00ea77613b942a9e08df6e3eb74b2ccd37641ba6)

Co-authored-by: Kumar Aditya <kumaraditya@python.org>
---

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 10e25bbdcdcb..c76721c5d2ac 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -3793,16 +3793,13 @@ list_ass_subscript_lock_held(PyObject *_self, PyObject *item, PyObject *value)
                     lim = Py_SIZE(self) - cur - 1;
                 }
 
-                memmove(self->ob_item + cur - i,
-                    self->ob_item + cur + 1,
-                    lim * sizeof(PyObject *));
+                ptr_wise_atomic_memmove(self, self->ob_item + cur - i,
+                    self->ob_item + cur + 1, lim);
             }
             cur = start + (size_t)slicelength * step;
             if (cur < (size_t)Py_SIZE(self)) {
-                memmove(self->ob_item + cur - slicelength,
-                    self->ob_item + cur,
-                    (Py_SIZE(self) - cur) *
-                     sizeof(PyObject *));
+                ptr_wise_atomic_memmove(self, self->ob_item + cur - slicelength,
+                    self->ob_item + cur, Py_SIZE(self) - cur);
             }
 
             Py_SET_SIZE(self, Py_SIZE(self) - slicelength);