From 4f00cfc82921e0e154d2b6aac63b785a6ac1cd49 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Mon, 20 Jan 2025 21:43:55 +0100
Subject: [PATCH] gh-111178: fix UBSan failures in
 `Modules/_multiprocessing/semaphore.c` (GH-129084)
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fix UBSan failures for `SemLockObject`
(cherry picked from commit 5ed5572cac7ef204767ddf8e8888e15672ba558e)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
---
 Modules/_multiprocessing/semaphore.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Modules/_multiprocessing/semaphore.c b/Modules/_multiprocessing/semaphore.c
index 4de4ee6c78fbd1..8c6a4a279205d3 100644
--- a/Modules/_multiprocessing/semaphore.c
+++ b/Modules/_multiprocessing/semaphore.c
@@ -27,6 +27,8 @@ typedef struct {
     char *name;
 } SemLockObject;
 
+#define _SemLockObject_CAST(op) ((SemLockObject *)(op))
+
 /*[python input]
 class SEM_HANDLE_converter(CConverter):
     type = "SEM_HANDLE"
@@ -575,8 +577,9 @@ _multiprocessing_SemLock__rebuild_impl(PyTypeObject *type, SEM_HANDLE handle,
 }
 
 static void
-semlock_dealloc(SemLockObject* self)
+semlock_dealloc(PyObject *op)
 {
+    SemLockObject *self = _SemLockObject_CAST(op);
     PyTypeObject *tp = Py_TYPE(self);
     PyObject_GC_UnTrack(self);
     if (self->handle != SEM_FAILED)
@@ -717,7 +720,7 @@ _multiprocessing_SemLock___exit___impl(SemLockObject *self,
 }
 
 static int
-semlock_traverse(SemLockObject *s, visitproc visit, void *arg)
+semlock_traverse(PyObject *s, visitproc visit, void *arg)
 {
     Py_VISIT(Py_TYPE(s));
     return 0;