From 9c3276e99bcb3227d98945f567b6c3a2f6921abe Mon Sep 17 00:00:00 2001
From: sweeneyde <sweeney.427@osu.edu>
Date: Mon, 18 Oct 2021 20:48:17 -0400
Subject: [PATCH 1/3] Use Py_EnterRecursiveCall() in issubclass()
---
Lib/test/test_isinstance.py | 21 +++++++++++++++++++++
Objects/abstract.c | 20 ++++++++++++++------
2 files changed, 35 insertions(+), 6 deletions(-)
diff --git a/Lib/test/test_isinstance.py b/Lib/test/test_isinstance.py
index 109c3f84a5c426..a2f2e6e9eb0788 100644
--- a/Lib/test/test_isinstance.py
+++ b/Lib/test/test_isinstance.py
@@ -313,6 +313,27 @@ def __bases__(self):
self.assertRaises(RecursionError, issubclass, int, X())
self.assertRaises(RecursionError, isinstance, 1, X())
+ def test_infinite_cycle_in_bases(self):
+ # bpo-30570
+ class X:
+ @property
+ def __bases__(self):
+ return (self, self, self)
+ self.assertRaises(RecursionError, issubclass, X(), int)
+
+ def test_infinitely_many_bases(self):
+ # 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/Objects/abstract.c b/Objects/abstract.c
index 6f7b94600e278a..6227ad5a18bb95 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
From 21c5b0fcb7fea97bd0438f72c99d5e2b15437554 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Tue, 19 Oct 2021 01:04:10 +0000
Subject: [PATCH 2/3] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
=?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
.../Core and Builtins/2021-10-19-01-04-08.bpo-30570._G30Ms.rst | 1 +
1 file changed, 1 insertion(+)
create mode 100644 Misc/NEWS.d/next/Core and Builtins/2021-10-19-01-04-08.bpo-30570._G30Ms.rst
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 00000000000000..d9ab60cd08f56d
--- /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
From f0cf002ee71fade314618242838c4fb4eb625330 Mon Sep 17 00:00:00 2001
From: "Gregory P. Smith" <greg@krypto.org>
Date: Fri, 22 Oct 2021 13:34:29 -0700
Subject: [PATCH 3/3] Add an additional test case.
---
Lib/test/test_isinstance.py | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/Lib/test/test_isinstance.py b/Lib/test/test_isinstance.py
index a2f2e6e9eb0788..6ab44be9a26ba7 100644
--- a/Lib/test/test_isinstance.py
+++ b/Lib/test/test_isinstance.py
@@ -313,8 +313,17 @@ def __bases__(self):
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):
- # bpo-30570
+ """Regression test for bpo-30570."""
class X:
@property
def __bases__(self):
@@ -322,7 +331,7 @@ def __bases__(self):
self.assertRaises(RecursionError, issubclass, X(), int)
def test_infinitely_many_bases(self):
- # bpo-30570
+ """Regression test for bpo-30570."""
class X:
def __getattr__(self, attr):
self.assertEqual(attr, "__bases__")