Issue #24257: Fixed incorrect uses of PyObject_IsInstance().

Fixed segmentation fault in sqlite3.Row constructor with faked cursor type.
Fixed system error in the comparison of faked types.SimpleNamespace.

2 files changed, 24 insertions, 0 deletions

diff --git a/Lib/sqlite3/test/factory.py b/Lib/sqlite3/test/factory.py
index 98dcae5d6c..a8348b4626 100644
--- a/Lib/sqlite3/test/factory.py
+++ b/Lib/sqlite3/test/factory.py
@@ -162,6 +162,14 @@ class RowFactoryTests(unittest.TestCase):
         self.assertEqual(list(reversed(row)), list(reversed(as_tuple)))
         self.assertIsInstance(row, Sequence)
 
+    def CheckFakeCursorClass(self):
+        # Issue #24257: Incorrect use of PyObject_IsInstance() caused
+        # segmentation fault.
+        class FakeCursor(str):
+            __class__ = sqlite.Cursor
+        cur = self.con.cursor(factory=FakeCursor)
+        self.assertRaises(TypeError, sqlite.Row, cur, ())
+
     def tearDown(self):
         self.con.close()
 
diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index ec10752e6a..849cba9649 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -1169,6 +1169,22 @@ class SimpleNamespaceTests(unittest.TestCase):
 
             self.assertEqual(ns, ns_roundtrip, pname)
 
+    def test_fake_namespace_compare(self):
+        # Issue #24257: Incorrect use of PyObject_IsInstance() caused
+        # SystemError.
+        class FakeSimpleNamespace(str):
+            __class__ = types.SimpleNamespace
+        self.assertFalse(types.SimpleNamespace() == FakeSimpleNamespace())
+        self.assertTrue(types.SimpleNamespace() != FakeSimpleNamespace())
+        with self.assertRaises(TypeError):
+            types.SimpleNamespace() < FakeSimpleNamespace()
+        with self.assertRaises(TypeError):
+            types.SimpleNamespace() <= FakeSimpleNamespace()
+        with self.assertRaises(TypeError):
+            types.SimpleNamespace() > FakeSimpleNamespace()
+        with self.assertRaises(TypeError):
+            types.SimpleNamespace() >= FakeSimpleNamespace()
+
 
 def test_main():
     run_unittest(TypesTests, MappingProxyTests, ClassCreationTests,