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[3.12] gh-115243: Fix crash in deque.index() when the deque is concurrently modified (GH-115247) (GH-115465)
(cherry picked from commit 6713601) Co-authored-by: kcatss <[email protected]>
1 parent 13af281 commit d258943

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3 files changed

+8
-2
lines changed

3 files changed

+8
-2
lines changed

Lib/test/test_deque.py

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -166,7 +166,7 @@ def test_contains(self):
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with self.assertRaises(RuntimeError):
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n in d
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169-
def test_contains_count_stop_crashes(self):
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def test_contains_count_index_stop_crashes(self):
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class A:
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def __eq__(self, other):
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d.clear()
@@ -178,6 +178,10 @@ def __eq__(self, other):
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with self.assertRaises(RuntimeError):
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_ = d.count(3)
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181+
d = deque([A()])
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with self.assertRaises(RuntimeError):
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d.index(0)
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def test_extend(self):
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d = deque('a')
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self.assertRaises(TypeError, d.extend, 1)
Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1 @@
1+
Fix possible crashes in :meth:`collections.deque.index` when the deque is concurrently modified.

Modules/_collectionsmodule.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1116,8 +1116,9 @@ deque_index(dequeobject *deque, PyObject *const *args, Py_ssize_t nargs)
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n = stop - i;
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while (--n >= 0) {
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CHECK_NOT_END(b);
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item = b->data[index];
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item = Py_NewRef(b->data[index]);
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cmp = PyObject_RichCompareBool(item, v, Py_EQ);
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Py_DECREF(item);
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if (cmp > 0)
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return PyLong_FromSsize_t(stop - n - 1);
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if (cmp < 0)

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