Stowage/cpython
2
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2026-02-14 03:10:44 +00:00
Code Issues Projects Releases Packages Wiki Activity

[3.13] GH-125789: fix fut._callbacks to always return a copy of callbacks (#125922) (#125976)

Browse source 
GH-125789: fix `fut._callbacks` to always return a copy of callbacks (#125922)

Fix `asyncio.Future._callbacks` to always return a copy of the internal list of callbacks to avoid mutation from user code affecting the internal state.

(cherry picked from commit cae853e3b4)
This commit is contained in:
Kumar Aditya 2024-10-25 18:49:31 +05:30 • committed by GitHub
parent b67358125c
commit f54e1a2d64
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
3 changed files with 44 additions and 28 deletions
Download patch file Download diff file Expand all files Collapse all files

18
Lib/test/test_asyncio/test_futures.py
View file

@ -705,6 +705,24 @@ def test_future_iter_get_referents_segfault(self):
evil = gc.get_referents(_asyncio)
gc.collect()
def test_callbacks_copy(self):
# See https://github.com/python/cpython/issues/125789
# In C implementation, the `_callbacks` attribute
# always returns a new list to avoid mutations of internal state
fut = self._new_future(loop=self.loop)
f1 = lambda _: 1
f2 = lambda _: 2
fut.add_done_callback(f1)
fut.add_done_callback(f2)
callbacks = fut._callbacks
self.assertIsNot(callbacks, fut._callbacks)
fut.remove_done_callback(f1)
callbacks = fut._callbacks
self.assertIsNot(callbacks, fut._callbacks)
fut.remove_done_callback(f2)
self.assertIsNone(fut._callbacks)
@unittest.skipUnless(hasattr(futures, '_CFuture'),
'requires the C _asyncio module')

1
Misc/NEWS.d/next/Library/2024-10-24-14-08-10.gh-issue-125789.eaiAMw.rst Normal file
View file

@ -0,0 +1 @@
Fix possible crash when mutating list of callbacks returned by :attr:`!asyncio.Future._callbacks`. It now always returns a new copy in C implementation :mod:`!_asyncio`. Patch by Kumar Aditya.

53
Modules/_asynciomodule.c
View file

@ -1211,52 +1211,49 @@ static PyObject *
FutureObj_get_callbacks(FutureObj *fut, void *Py_UNUSED(ignored))
{
asyncio_state *state = get_asyncio_state_by_def((PyObject *)fut);
Py_ssize_t i;
ENSURE_FUTURE_ALIVE(state, fut)
if (fut->fut_callback0 == NULL) {
if (fut->fut_callbacks == NULL) {
Py_RETURN_NONE;
}
return Py_NewRef(fut->fut_callbacks);
Py_ssize_t len = 0;
if (fut->fut_callback0 != NULL) {
len++;
}
Py_ssize_t len = 1;
if (fut->fut_callbacks != NULL) {
len += PyList_GET_SIZE(fut->fut_callbacks);
}
if (len == 0) {
Py_RETURN_NONE;
}
PyObject *new_list = PyList_New(len);
if (new_list == NULL) {
PyObject *callbacks = PyList_New(len);
if (callbacks == NULL) {
return NULL;
}
PyObject *tup0 = PyTuple_New(2);
if (tup0 == NULL) {
Py_DECREF(new_list);
return NULL;
Py_ssize_t i = 0;
if (fut->fut_callback0 != NULL) {
PyObject *tup0 = PyTuple_New(2);
if (tup0 == NULL) {
Py_DECREF(callbacks);
return NULL;
}
PyTuple_SET_ITEM(tup0, 0, Py_NewRef(fut->fut_callback0));
assert(fut->fut_context0 != NULL);
PyTuple_SET_ITEM(tup0, 1, Py_NewRef(fut->fut_context0));
PyList_SET_ITEM(callbacks, i, tup0);
i++;
}
Py_INCREF(fut->fut_callback0);
PyTuple_SET_ITEM(tup0, 0, fut->fut_callback0);
assert(fut->fut_context0 != NULL);
Py_INCREF(fut->fut_context0);
PyTuple_SET_ITEM(tup0, 1, (PyObject *)fut->fut_context0);
PyList_SET_ITEM(new_list, 0, tup0);
if (fut->fut_callbacks != NULL) {
for (i = 0; i < PyList_GET_SIZE(fut->fut_callbacks); i++) {
PyObject *cb = PyList_GET_ITEM(fut->fut_callbacks, i);
for (Py_ssize_t j = 0; j < PyList_GET_SIZE(fut->fut_callbacks); j++) {
PyObject *cb = PyList_GET_ITEM(fut->fut_callbacks, j);
Py_INCREF(cb);
PyList_SET_ITEM(new_list, i + 1, cb);
PyList_SET_ITEM(callbacks, i, cb);
i++;
}
}
return new_list;
return callbacks;
}
static PyObject *