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gh-120298: Fix use-after-free in `list_richcompare_impl` (#120303) 

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
This commit is contained in:
Nikita Sobolev 2024-06-11 10:04:27 +03:00 committed by GitHub
parent 9e9ee50421
commit 141babad9b
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3 changed files with 21 additions and 1 deletions
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11
Lib/test/test_list.py
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@ -234,6 +234,17 @@ class ListTest(list_tests.CommonTest):
list4 = [1] list4 = [1]
self.assertFalse(list3 == list4) self.assertFalse(list3 == list4)
def test_lt_operator_modifying_operand(self):
# See gh-120298
class evil:
def __lt__(self, other):
other.clear()
return NotImplemented
a = [[evil()]]
with self.assertRaises(TypeError):
a[0] < a
@cpython_only @cpython_only
def test_preallocation(self): def test_preallocation(self):
iterable = [0] * 10 iterable = [0] * 10

2
Misc/NEWS.d/next/Core and Builtins/2024-06-10-10-42-48.gh-issue-120298.napREA.rst Normal file
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@ -0,0 +1,2 @@
Fix use-after free in ``list_richcompare_impl`` which can be invoked via
some specificly tailored evil input.

9
Objects/listobject.c
View File

@ -3382,7 +3382,14 @@ list_richcompare_impl(PyObject *v, PyObject *w, int op)
} }
/* Compare the final item again using the proper operator */ /* Compare the final item again using the proper operator */
return PyObject_RichCompare(vl->ob_item[i], wl->ob_item[i], op); PyObject *vitem = vl->ob_item[i];
PyObject *witem = wl->ob_item[i];
Py_INCREF(vitem);
Py_INCREF(witem);
PyObject *result = PyObject_RichCompare(vl->ob_item[i], wl->ob_item[i], op);
Py_DECREF(vitem);
Py_DECREF(witem);
return result;
} }
static PyObject * static PyObject *