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From 05ee790f4d1cd8725a90b54268fc1dfe5b4d1fa2 Mon Sep 17 00:00:00 2001
From: Ronald Oussoren <ronaldoussoren@mac.com>
Date: Mon, 19 Oct 2020 20:13:49 +0200
Subject: [PATCH] bpo-42051: Reject XML entity declarations in plist files
(#22760)
---
Lib/plistlib.py | 7 +++++++
Lib/test/test_plistlib.py | 18 ++++++++++++++++++
.../2020-10-19-10-56-27.bpo-42051.EU_B7u.rst | 3 +++
3 files changed, 28 insertions(+)
create mode 100644 Misc/NEWS.d/next/Security/2020-10-19-10-56-27.bpo-42051.EU_B7u.rst
Backport:
* Drop Misc/NEWS.d
* plistlib.py:
* Handle cAmElCaSe vs under_scores
* self.parser vs parser
* Degrade InvalidFileException to ValueError
* test_plistlib.py:
* Update hunk context
* Drop b"" prefix
* Degrade InvalidFileException to ValueError
* Adapt parser invocation to older API
* Reimplement assertRaisesRegexp
diff --git a/Lib/plistlib.py b/Lib/plistlib.py
index aff5fe36ca..ba7ac19364 100644
--- a/Lib/plistlib.py
+++ b/Lib/plistlib.py
@@ -173,9 +173,16 @@ def parse(self, fileobj):
parser.StartElementHandler = self.handleBeginElement
parser.EndElementHandler = self.handleEndElement
parser.CharacterDataHandler = self.handleData
+ parser.EntityDeclHandler = self.handleEntityDecl
parser.ParseFile(fileobj)
return self.root
+ def handleEntityDecl(self, entity_name, is_parameter_entity, value, base, system_id, public_id, notation_name):
+ # Reject plist files with entity declarations to avoid XML vulnerabilies in expat.
+ # Regular plist files don't contain those declerations, and Apple's plutil tool does not
+ # accept them either.
+ raise ValueError("XML entity declarations are not supported in plist files")
+
def handleBeginElement(self, element, attrs):
self.data = []
handler = getattr(self, "begin_" + element, None)
diff --git a/Lib/test/test_plistlib.py b/Lib/test/test_plistlib.py
index e5c9b5b6b2..cb071da1f3 100644
--- a/Lib/test/test_plistlib.py
+++ b/Lib/test/test_plistlib.py
@@ -106,6 +106,19 @@
</plist>
""".replace(" " * 8, "\t") # Apple as well as plistlib.py output hard tabs
+XML_PLIST_WITH_ENTITY='''\
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd" [
+ <!ENTITY entity "replacement text">
+ ]>
+<plist version="1.0">
+ <dict>
+ <key>A</key>
+ <string>&entity;</string>
+ </dict>
+</plist>
+'''
+
class TestPlistlib(unittest.TestCase):
@@ -524,6 +537,15 @@ def test_modified_uid_huge(self):
self.assertEqual(test1, result1)
self.assertEqual(test2, result2)
+ def test_xml_plist_with_entity_decl(self):
+ try:
+ plistlib.readPlistFromString(XML_PLIST_WITH_ENTITY)
+ except ValueError as e:
+ self.assertIn("XML entity declarations are not supported",
+ e.message)
+ else:
+ self.fail("expected ValueError to be raised")
+
def test_main():
test_support.run_unittest(TestPlistlib)
--
2.40.1
|
