From 04c0dc93569a52f3e62d2f8a2871790b274de13f Mon Sep 17 00:00:00 2001 From: Jelle Zijlstra Date: Tue, 20 Oct 2026 21:34:23 -0700 Subject: [PATCH] gh-159739: Fix reference and error handling in warnings (GH-159758) Do not release the borrowed skip_file_prefixes argument, and stop if allocation of the fallback filename fails. (cherry picked from commit fab1405da8c93429ab1a1d3d3e1779d15b7223a2) Co-authored-by: Jelle Zijlstra --- Lib/test/test_warnings/__init__.py | 14 ++++++++++++++ .../2026-10-19-19-33-35.gh-issue-159739.f81734.rst | 2 ++ Python/_warnings.c | 4 +++- 3 files changed, 19 insertions(+), 1 deletion(-) create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.f81734.rst diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py index c9aff12e596366f..a70fd4c96813c17 100644 --- a/Lib/test/test_warnings/__init__.py +++ b/Lib/test/test_warnings/__init__.py @@ -697,6 +697,20 @@ def test_skip_file_prefixes_type_errors(self): with self.assertRaises(TypeError): warn("msg", skip_file_prefixes="a sequence of strs") + def test_skip_file_prefixes_empty_tuple_subclass(self): + with warnings_state(self.module): + self.module.simplefilter("always") + warn = warning_tests.warnings.warn + class EmptyTuple(tuple): + pass + # Passing an empty tuple subclass used to lead to a crash. + for _ in range(3): + with self.module.catch_warnings(record=True) as w: + warn("msg", skip_file_prefixes=EmptyTuple()) + self.assertEqual(len(w), 1) + self.assertEqual(w[-1].filename, __file__) + self.assertEqual(w[-1].module, __name__) + def test_exec_filename_module(self): filename = "" codeobj = compile(("import warnings\n" diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.f81734.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.f81734.rst new file mode 100644 index 000000000000000..0342bdef3e86994 --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.f81734.rst @@ -0,0 +1,2 @@ +Fix a crash in :func:`warnings.warn` when ``skip_file_prefixes`` is an empty tuple subclass. +Propagate allocation errors when creating the fallback filename. diff --git a/Python/_warnings.c b/Python/_warnings.c index dd48f740d261764..c2fb0f120d05c0a 100644 --- a/Python/_warnings.c +++ b/Python/_warnings.c @@ -1058,6 +1058,9 @@ setup_context(Py_ssize_t stack_level, if (f == NULL) { globals = interp->sysdict; *filename = PyUnicode_FromString(""); + if (*filename == NULL) { + return 0; + } *lineno = 0; } else { @@ -1201,7 +1204,6 @@ warnings_warn_impl(PyObject *module, PyObject *message, PyObject *category, stacklevel = 2; } } else { - Py_DECREF((PyObject *)skip_file_prefixes); skip_file_prefixes = NULL; } }