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authorDennis Sweeney <36520290+sweeneyde@users.noreply.github.com>2021-10-22 21:24:08 (GMT)
committerGitHub <noreply@github.com>2021-10-22 21:24:08 (GMT)
commit423fa1c1817abfa8c3d1bc308ddbbd8f28b69d68 (patch)
tree416e4d37e4761b89012aa7dd001a923182081f67
parentf6e8b80d20159596cf641305bad3a833bedd2f4f (diff)
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bpo-30570: Use Py_EnterRecursiveCall() in issubclass() (GH-29048)
* Use Py_EnterRecursiveCall() in issubclass() Reviewed-by: Gregory P. Smith <greg@krypto.org> [Google]
-rw-r--r--Lib/test/test_isinstance.py30
-rw-r--r--Misc/NEWS.d/next/Core and Builtins/2021-10-19-01-04-08.bpo-30570._G30Ms.rst1
-rw-r--r--Objects/abstract.c20
3 files changed, 45 insertions, 6 deletions
diff --git a/Lib/test/test_isinstance.py b/Lib/test/test_isinstance.py
index 109c3f8..6ab44be 100644
--- a/Lib/test/test_isinstance.py
+++ b/Lib/test/test_isinstance.py
@@ -313,6 +313,36 @@ class TestIsInstanceIsSubclass(unittest.TestCase):
self.assertRaises(RecursionError, issubclass, int, X())
self.assertRaises(RecursionError, isinstance, 1, X())
+ def test_infinite_recursion_via_bases_tuple(self):
+ """Regression test for bpo-30570."""
+ class Failure(object):
+ def __getattr__(self, attr):
+ return (self, None)
+
+ with self.assertRaises(RecursionError):
+ issubclass(Failure(), int)
+
+ def test_infinite_cycle_in_bases(self):
+ """Regression test for bpo-30570."""
+ class X:
+ @property
+ def __bases__(self):
+ return (self, self, self)
+ self.assertRaises(RecursionError, issubclass, X(), int)
+
+ def test_infinitely_many_bases(self):
+ """Regression test for bpo-30570."""
+ class X:
+ def __getattr__(self, attr):
+ self.assertEqual(attr, "__bases__")
+ class A:
+ pass
+ class B:
+ pass
+ A.__getattr__ = B.__getattr__ = X.__getattr__
+ return (A(), B())
+ self.assertRaises(RecursionError, issubclass, X(), int)
+
def blowstack(fxn, arg, compare_to):
# Make sure that calling isinstance with a deeply nested tuple for its
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-10-19-01-04-08.bpo-30570._G30Ms.rst b/Misc/NEWS.d/next/Core and Builtins/2021-10-19-01-04-08.bpo-30570._G30Ms.rst
new file mode 100644
index 0000000..d9ab60c
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-10-19-01-04-08.bpo-30570._G30Ms.rst
@@ -0,0 +1 @@
+Fixed a crash in ``issubclass()`` from infinite recursion when searching pathological ``__bases__`` tuples. \ No newline at end of file
diff --git a/Objects/abstract.c b/Objects/abstract.c
index 6f7b946..6227ad5 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -2557,14 +2557,22 @@ abstract_issubclass(PyObject *derived, PyObject *cls)
derived = PyTuple_GET_ITEM(bases, 0);
continue;
}
- for (i = 0; i < n; i++) {
- r = abstract_issubclass(PyTuple_GET_ITEM(bases, i), cls);
- if (r != 0)
- break;
- }
+ break;
+ }
+ assert(n >= 2);
+ if (Py_EnterRecursiveCall(" in __issubclass__")) {
Py_DECREF(bases);
- return r;
+ return -1;
}
+ for (i = 0; i < n; i++) {
+ r = abstract_issubclass(PyTuple_GET_ITEM(bases, i), cls);
+ if (r != 0) {
+ break;
+ }
+ }
+ Py_LeaveRecursiveCall();
+ Py_DECREF(bases);
+ return r;
}
static int