From 3ccc7d583e325ceb0ebdf8fc295bbb7fc8cd404d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miro=20Hron=C4=8Dok?= <miro@hroncok.cz>
Date: Sat, 2 Mar 2024 06:51:01 +0100
Subject: [PATCH] Fix test_elementtree with Expat 2.6.0 (GH-407)

Feeding the parser by too small chunks defers parsing to prevent
CVE-2023-52425. Future versions of Expat may be more reactive.

Heavily inspired by https://github.com/python/cpython/commit/4a08e7b3431cd32a0daf22a33421cd3035343dc4

We cannot use a @fails_with_expat_2_6_0 decorator
because the test passes in ETreePullTestCase.

See https://github.com/python/cpython/issues/115133
See https://github.com/advisories/GHSA-gh68-jm46-84rf
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
---
 src/lxml/tests/test_elementtree.py | 62 +++++++++++++++++++-----------
 1 file changed, 39 insertions(+), 23 deletions(-)

diff --git a/src/lxml/tests/test_elementtree.py b/src/lxml/tests/test_elementtree.py
index 8ccf4442a..ef923c5ce 100644
--- a/src/lxml/tests/test_elementtree.py
+++ b/src/lxml/tests/test_elementtree.py
@@ -10,6 +10,7 @@
 import io
 import operator
 import os
+import pyexpat
 import re
 import sys
 import textwrap
@@ -4383,29 +4384,44 @@ def assert_event_tags(self, parser, expected, max_events=None):
         self.assertEqual([(action, elem.tag) for action, elem in events],
                          expected)
 
-    def test_simple_xml(self):
-        for chunk_size in (None, 1, 5):
-            #with self.subTest(chunk_size=chunk_size):
-                parser = self.etree.XMLPullParser()
-                self.assert_event_tags(parser, [])
-                self._feed(parser, "<!-- comment -->\n", chunk_size)
-                self.assert_event_tags(parser, [])
-                self._feed(parser,
-                           "<root>\n  <element key='value'>text</element",
-                           chunk_size)
-                self.assert_event_tags(parser, [])
-                self._feed(parser, ">\n", chunk_size)
-                self.assert_event_tags(parser, [('end', 'element')])
-                self._feed(parser, "<element>text</element>tail\n", chunk_size)
-                self._feed(parser, "<empty-element/>\n", chunk_size)
-                self.assert_event_tags(parser, [
-                    ('end', 'element'),
-                    ('end', 'empty-element'),
-                    ])
-                self._feed(parser, "</root>\n", chunk_size)
-                self.assert_event_tags(parser, [('end', 'root')])
-                root = self._close_and_return_root(parser)
-                self.assertEqual(root.tag, 'root')
+    def test_simple_xml(self, chunk_size=None):
+        parser = self.etree.XMLPullParser()
+        self.assert_event_tags(parser, [])
+        self._feed(parser, "<!-- comment -->\n", chunk_size)
+        self.assert_event_tags(parser, [])
+        self._feed(parser,
+                   "<root>\n  <element key='value'>text</element",
+                   chunk_size)
+        self.assert_event_tags(parser, [])
+        self._feed(parser, ">\n", chunk_size)
+        self.assert_event_tags(parser, [('end', 'element')])
+        self._feed(parser, "<element>text</element>tail\n", chunk_size)
+        self._feed(parser, "<empty-element/>\n", chunk_size)
+        self.assert_event_tags(parser, [
+            ('end', 'element'),
+            ('end', 'empty-element'),
+            ])
+        self._feed(parser, "</root>\n", chunk_size)
+        self.assert_event_tags(parser, [('end', 'root')])
+        root = self._close_and_return_root(parser)
+        self.assertEqual(root.tag, 'root')
+
+    def test_simple_xml_chunk_1(self):
+        if self.etree is not etree and pyexpat.version_info >= (2, 6, 0):
+            raise unittest.SkipTest(
+                "Feeding the parser by too small chunks defers parsing"
+            )
+        self.test_simple_xml(chunk_size=1)
+
+    def test_simple_xml_chunk_5(self):
+        if self.etree is not etree and pyexpat.version_info >= (2, 6, 0):
+            raise unittest.SkipTest(
+                "Feeding the parser by too small chunks defers parsing"
+            )
+        self.test_simple_xml(chunk_size=5)
+
+    def test_simple_xml_chunk_22(self):
+        self.test_simple_xml(chunk_size=22)
 
     def test_feed_while_iterating(self):
         parser = self.etree.XMLPullParser()