From: Tomasz Pytel <tompytel@gmail.com>
Date: Wed, 12 Feb 2025 13:04:44 +0000 (-0500)
Subject: gh-129983: fix data race in compile_template in sre.c (#130015)
X-Git-Tag: v3.14.0a6~453
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3cf68cdd3e1809df4e426c61f6990de63747ec6f;p=thirdparty%2FPython%2Fcpython.git

gh-129983: fix data race in compile_template in sre.c (#130015)
---

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-02-11-20-38-37.gh-issue-129983._1Fujo.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-02-11-20-38-37.gh-issue-129983._1Fujo.rst
new file mode 100644
index 000000000000..9b435703eb73
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-02-11-20-38-37.gh-issue-129983._1Fujo.rst
@@ -0,0 +1 @@
+Fix data race in compile_template in :file:`sre.c`.
diff --git a/Modules/_sre/sre.c b/Modules/_sre/sre.c
index 0d8d4843d33c..54f0e64d4819 100644
--- a/Modules/_sre/sre.c
+++ b/Modules/_sre/sre.c
@@ -1167,13 +1167,21 @@ compile_template(_sremodulestate *module_state,
                  PatternObject *pattern, PyObject *template)
 {
     /* delegate to Python code */
-    PyObject *func = module_state->compile_template;
+    PyObject *func = FT_ATOMIC_LOAD_PTR(module_state->compile_template);
     if (func == NULL) {
         func = PyImport_ImportModuleAttrString("re", "_compile_template");
         if (func == NULL) {
             return NULL;
         }
+#ifdef Py_GIL_DISABLED
+        PyObject *other_func = NULL;
+        if (!_Py_atomic_compare_exchange_ptr(&module_state->compile_template, &other_func, func))  {
+            Py_DECREF(func);
+            func = other_func;
+        }
+#else
         Py_XSETREF(module_state->compile_template, func);
+#endif
     }
 
     PyObject *args[] = {(PyObject *)pattern, template};