From d60c33b2a4e4f9ab9cae547826f9561d90290124 Mon Sep 17 00:00:00 2001 From: Sam Gross Date: Thu, 9 May 2024 14:52:27 -0400 Subject: [PATCH] gh-118561: Fix crash involving list.extend in free-threaded build (GH-118723) The `list_preallocate_exact` function did not zero initialize array contents. In the free-threaded build, this could expose uninitialized memory to concurrent readers between the call to `list_preallocate_exact` and the filling of the array contents with items. (cherry picked from commit 2402715e10d00ef60fad2948d8461559d084eb36) Co-authored-by: Sam Gross --- .../2024-05-07-16-57-56.gh-issue-118561.wNMKVd.rst | 2 ++ Objects/listobject.c | 3 ++- 2 files changed, 4 insertions(+), 1 deletion(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2024-05-07-16-57-56.gh-issue-118561.wNMKVd.rst diff --git a/Misc/NEWS.d/next/Core and Builtins/2024-05-07-16-57-56.gh-issue-118561.wNMKVd.rst b/Misc/NEWS.d/next/Core and Builtins/2024-05-07-16-57-56.gh-issue-118561.wNMKVd.rst new file mode 100644 index 00000000000000..9eaf0abb8a6128 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2024-05-07-16-57-56.gh-issue-118561.wNMKVd.rst @@ -0,0 +1,2 @@ +Fix race condition in free-threaded build where :meth:`list.extend` could expose +uninitialied memory to concurrent readers. diff --git a/Objects/listobject.c b/Objects/listobject.c index 3c4e2d2e6ed7de..7070165014f137 100644 --- a/Objects/listobject.c +++ b/Objects/listobject.c @@ -192,6 +192,7 @@ list_preallocate_exact(PyListObject *self, Py_ssize_t size) return -1; } items = array->ob_item; + memset(items, 0, size * sizeof(PyObject *)); #else items = PyMem_New(PyObject*, size); if (items == NULL) { @@ -199,7 +200,7 @@ list_preallocate_exact(PyListObject *self, Py_ssize_t size) return -1; } #endif - self->ob_item = items; + FT_ATOMIC_STORE_PTR_RELEASE(self->ob_item, items); self->allocated = size; return 0; } pFad - Phonifier reborn

Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.

Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.

Alternative Proxies:

Alternative Proxy

pFad Proxy

pFad v3 Proxy

pFad v4 Proxy