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[3.8] bpo-39453: Fix contains method of list to hold strong references (GH-18204)

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Dong-hee Na 2020-02-17 18:13:52 +09:00 committed by GitHub
parent 988aeba94b
commit f64abd1056
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3 changed files with 16 additions and 3 deletions
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7
Lib/test/test_list.py
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@ -216,6 +216,13 @@ class ListTest(list_tests.CommonTest):
with self.assertRaises(ValueError):
lst.remove(lst)
# bpo-39453: list.__contains__ was not holding strong references
# to list elements while calling PyObject_RichCompareBool().
lst = [X(), X()]
3 in lst
lst = [X(), X()]
X() in lst
if __name__ == "__main__":
unittest.main()

2
Misc/NEWS.d/next/Core and Builtins/2020-01-25-23-51-17.bpo-39453.xCOkYk.rst Normal file
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@ -0,0 +1,2 @@
Fixed a possible crash in :meth:`list.__contains__` when a list is changed
during comparing items. Patch by Dong-hee Na.

10
Objects/listobject.c
View File

@ -445,12 +445,16 @@ list_length(PyListObject *a)
static int
list_contains(PyListObject *a, PyObject *el)
{
PyObject *item;
Py_ssize_t i;
int cmp;
for (i = 0, cmp = 0 ; cmp == 0 && i < Py_SIZE(a); ++i)
cmp = PyObject_RichCompareBool(el, PyList_GET_ITEM(a, i),
Py_EQ);
for (i = 0, cmp = 0 ; cmp == 0 && i < Py_SIZE(a); ++i) {
item = PyList_GET_ITEM(a, i);
Py_INCREF(item);
cmp = PyObject_RichCompareBool(el, item, Py_EQ);
Py_DECREF(item);
}
return cmp;
}