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| author |   Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> | 2020-02-22 05:34:06 -0800 |
|---|---|---|
| committer |   GitHub <noreply@github.com> | 2020-02-22 05:34:06 -0800 |
| commit | 0c1827e70c1c05ce1982a34380cea7d391904293 (patch) | |
| tree | e253ef69b53e82c3838142390fcaf054dff0fc8e /Objects | |
| parent | bpo-39576: docs: set context for decimal arbitrary precision arithmetic (GH-1... (diff) | |
| download | cpython-0c1827e70c1c05ce1982a34380cea7d391904293.tar.gz cpython-0c1827e70c1c05ce1982a34380cea7d391904293.tar.bz2 cpython-0c1827e70c1c05ce1982a34380cea7d391904293.zip | |
bpo-39382: Avoid dangling object use in abstract_issubclass() (GH-18530)
Hold reference of __bases__ tuple until tuple item is done with, because by
dropping the reference the item may be destroyed.
(cherry picked from commit 1c56f8ffad44478b4214a2bf8eb7cf51c28a347a)
Co-authored-by: Yonatan Goldschmidt <yon.goldschmidt@gmail.com>
Diffstat (limited to 'Objects')
| -rw-r--r-- | Objects/abstract.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/Objects/abstract.c b/Objects/abstract.c index 77d09143aa0..bc1ebd930c0 100644 --- a/Objects/abstract.c +++ b/Objects/abstract.c @@ -2336,9 +2336,16 @@ abstract_issubclass(PyObject *derived, PyObject *cls) int r = 0; while (1) { - if (derived == cls) + if (derived == cls) { + Py_XDECREF(bases); /* See below comment */ return 1; - bases = abstract_get_bases(derived); + } + /* Use XSETREF to drop bases reference *after* finishing with + derived; bases might be the only reference to it. + XSETREF is used instead of SETREF, because bases is NULL on the + first iteration of the loop. + */ + Py_XSETREF(bases, abstract_get_bases(derived)); if (bases == NULL) { if (PyErr_Occurred()) return -1; @@ -2352,7 +2359,6 @@ abstract_issubclass(PyObject *derived, PyObject *cls) /* Avoid recursivity in the single inheritance case */ if (n == 1) { derived = PyTuple_GET_ITEM(bases, 0); - Py_DECREF(bases); continue; } for (i = 0; i < n; i++) { |