From 5db5c26ae4dffc7bae21c38d89b6c005d48474f9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ga=C3=ABl=20Delalleau?=
 <21263019+gaeldelalleau@users.noreply.github.com>
Date: Wed, 31 Jul 2019 23:52:53 +0200
Subject: [PATCH] Fix a Python extension crash in the descriptor's nested types
 container code (#6455)

---
 python/google/protobuf/internal/descriptor_test.py    | 7 +++++++
 python/google/protobuf/pyext/descriptor_containers.cc | 1 +
 2 files changed, 8 insertions(+)

diff --git a/python/google/protobuf/internal/descriptor_test.py b/python/google/protobuf/internal/descriptor_test.py
index e753cbabd4..35d635e0b6 100755
--- a/python/google/protobuf/internal/descriptor_test.py
+++ b/python/google/protobuf/internal/descriptor_test.py
@@ -650,6 +650,13 @@ class GeneratedDescriptorTest(unittest.TestCase):
     del enum
     self.assertEqual('FOO', next(values_iter).name)
 
+  def testDescriptorNestedTypesContainer(self):
+    message_descriptor = unittest_pb2.TestAllTypes.DESCRIPTOR
+    nested_message_descriptor = unittest_pb2.TestAllTypes.NestedMessage.DESCRIPTOR
+    self.assertEqual(len(message_descriptor.nested_types), 3)
+    self.assertFalse(None in message_descriptor.nested_types)
+    self.assertTrue(nested_message_descriptor in message_descriptor.nested_types)
+
   def testServiceDescriptor(self):
     service_descriptor = unittest_pb2.DESCRIPTOR.services_by_name['TestService']
     self.assertEqual(service_descriptor.name, 'TestService')
diff --git a/python/google/protobuf/pyext/descriptor_containers.cc b/python/google/protobuf/pyext/descriptor_containers.cc
index d5b5dc6817..8be8468164 100644
--- a/python/google/protobuf/pyext/descriptor_containers.cc
+++ b/python/google/protobuf/pyext/descriptor_containers.cc
@@ -639,6 +639,7 @@ int Find(PyContainer* self, PyObject* item) {
   // the .proto file definition.
   const void* descriptor_ptr = PyDescriptor_AsVoidPtr(item);
   if (descriptor_ptr == NULL) {
+    PyErr_Clear();
     // Not a descriptor, it cannot be in the list.
     return -1;
   }