bpo-43660: Fix crash when displaying exceptions with custom values for sys.stderr (GH-25075)
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 5b004c2..ee39375 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1512,6 +1512,21 @@ def test_asyncgen_hooks(self):
self.assertIsNone(cur.firstiter)
self.assertIsNone(cur.finalizer)
+ def test_changing_sys_stderr_and_removing_reference(self):
+ # If the default displayhook doesn't take a strong reference
+ # to sys.stderr the following code can crash. See bpo-43660
+ # for more details.
+ code = textwrap.dedent('''
+ import sys
+ class MyStderr:
+ def write(self, s):
+ sys.stderr = None
+ sys.stderr = MyStderr()
+ 1/0
+ ''')
+ rc, out, err = assert_python_failure('-c', code)
+ self.assertEqual(out, b"")
+ self.assertEqual(err, b"")
if __name__ == "__main__":
unittest.main()
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-03-29-19-50-34.bpo-43660.scTgag.rst b/Misc/NEWS.d/next/Core and Builtins/2021-03-29-19-50-34.bpo-43660.scTgag.rst
new file mode 100644
index 0000000..9841950
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-03-29-19-50-34.bpo-43660.scTgag.rst
@@ -0,0 +1,3 @@
+Fix crash that happens when replacing ``sys.stderr`` with a callable that
+can remove the object while an exception is being printed. Patch by Pablo
+Galindo.
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index b562875..1715cde 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1082,8 +1082,9 @@ PyErr_Display(PyObject *exception, PyObject *value, PyObject *tb)
if (file == Py_None) {
return;
}
-
+ Py_INCREF(file);
_PyErr_Display(file, exception, value, tb);
+ Py_DECREF(file);
}
PyObject *