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gh-128130: Fix unhandled keyboard interrupt data race (gh-129975)

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Use an atomic operation when setting
`_PyRuntime.signals.unhandled_keyboard_interrupt`. We now only clear the
variable at the start of `_PyRun_Main`, which is the same function where
we check it.

This avoids race conditions where previously another thread might call
`run_eval_code_obj()` and erroneously clear the unhandled keyboard
interrupt.
This commit is contained in:
Sam Gross 2025-02-13 12:29:03 -05:00 • committed by GitHub
parent aa28423201
commit 451f291baa
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GPG key ID: B5690EEEBB952194
4 changed files with 13 additions and 36 deletions
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33
Python/pythonrun.c
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@ -589,8 +589,13 @@ parse_exit_code(PyObject *code, int *exitcode_p)
}
int
_Py_HandleSystemExit(int *exitcode_p)
_Py_HandleSystemExitAndKeyboardInterrupt(int *exitcode_p)
{
if (PyErr_ExceptionMatches(PyExc_KeyboardInterrupt)) {
_Py_atomic_store_int(&_PyRuntime.signals.unhandled_keyboard_interrupt, 1);
return 0;
}
int inspect = _Py_GetConfig()->inspect;
if (inspect) {
/* Don't exit if -i flag was given. This flag is set to 0
@ -646,7 +651,7 @@ static void
handle_system_exit(void)
{
int exitcode;
if (_Py_HandleSystemExit(&exitcode)) {
if (_Py_HandleSystemExitAndKeyboardInterrupt(&exitcode)) {
Py_Exit(exitcode);
}
}
@ -1105,8 +1110,6 @@ _PyErr_Display(PyObject *file, PyObject *unused, PyObject *value, PyObject *tb)
}
}
int unhandled_keyboard_interrupt = _PyRuntime.signals.unhandled_keyboard_interrupt;
// Try first with the stdlib traceback module
PyObject *print_exception_fn = PyImport_ImportModuleAttrString(
"traceback",
@ -1120,11 +1123,9 @@ _PyErr_Display(PyObject *file, PyObject *unused, PyObject *value, PyObject *tb)
Py_XDECREF(print_exception_fn);
if (result) {
Py_DECREF(result);
_PyRuntime.signals.unhandled_keyboard_interrupt = unhandled_keyboard_interrupt;
return;
}
fallback:
_PyRuntime.signals.unhandled_keyboard_interrupt = unhandled_keyboard_interrupt;
#ifdef Py_DEBUG
if (PyErr_Occurred()) {
PyErr_FormatUnraisable(
@ -1297,20 +1298,6 @@ flush_io(void)
static PyObject *
run_eval_code_obj(PyThreadState *tstate, PyCodeObject *co, PyObject *globals, PyObject *locals)
{
PyObject *v;
/*
* We explicitly re-initialize _Py_UnhandledKeyboardInterrupt every eval
* _just in case_ someone is calling into an embedded Python where they
* don't care about an uncaught KeyboardInterrupt exception (why didn't they
* leave config.install_signal_handlers set to 0?!?) but then later call
* Py_Main() itself (which _checks_ this flag and dies with a signal after
* its interpreter exits). We don't want a previous embedded interpreter's
* uncaught exception to trigger an unexplained signal exit from a future
* Py_Main() based one.
*/
// XXX Isn't this dealt with by the move to _PyRuntimeState?
_PyRuntime.signals.unhandled_keyboard_interrupt = 0;
/* Set globals['__builtins__'] if it doesn't exist */
if (!globals || !PyDict_Check(globals)) {
PyErr_SetString(PyExc_SystemError, "globals must be a real dict");
@ -1328,11 +1315,7 @@ run_eval_code_obj(PyThreadState *tstate, PyCodeObject *co, PyObject *globals, Py
}
}
v = PyEval_EvalCode((PyObject*)co, globals, locals);
if (!v && _PyErr_Occurred(tstate) == PyExc_KeyboardInterrupt) {
_PyRuntime.signals.unhandled_keyboard_interrupt = 1;
}
return v;
return PyEval_EvalCode((PyObject*)co, globals, locals);
}
static PyObject *