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From 9c9dda6625a2a90d2a06c657eee021d6be19842d Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
<31488909+miss-islington@users.noreply.github.com>
Date: Mon, 22 Dec 2025 14:48:49 +0100
Subject: [PATCH] [3.12] gh-142145: Remove quadratic behavior in node ID cache
clearing (GH-142146) (#142211)
* gh-142145: Remove quadratic behavior in node ID cache clearing (GH-142146)
* gh-142754: Ensure that Element & Attr instances have the ownerDocument attribute (GH-142794)
(cherry picked from commit 1cc7551b3f9f71efbc88d96dce90f82de98b2454)
(cherry picked from commit 08d8e18ad81cd45bc4a27d6da478b51ea49486e4)
(cherry picked from commit 8d2d7bb2e754f8649a68ce4116271a4932f76907)
Co-authored-by: Jacob Walls <38668450+jacobtylerwalls@users.noreply.github.com>
Co-authored-by: Seth Michael Larson <seth@python.org>
Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
CVE: CVE-2025-12084
Upstream-Status: Backport [https://github.com/python/cpython/commit/9c9dda6625a2a90d2a06c657eee021d6be19842d]
Signed-off-by: Peter Marko <peter.marko@siemens.com>
---
Lib/test/test_minidom.py | 33 ++++++++++++++++++-
Lib/xml/dom/minidom.py | 11 ++-----
...-12-01-09-36-45.gh-issue-142145.tcAUhg.rst | 6 ++++
3 files changed, 41 insertions(+), 9 deletions(-)
create mode 100644 Misc/NEWS.d/next/Security/2025-12-01-09-36-45.gh-issue-142145.tcAUhg.rst
diff --git a/Lib/test/test_minidom.py b/Lib/test/test_minidom.py
index 699265ccadc..ab4823c8315 100644
--- a/Lib/test/test_minidom.py
+++ b/Lib/test/test_minidom.py
@@ -2,13 +2,14 @@
import copy
import pickle
+import time
import io
from test import support
import unittest
import xml.dom.minidom
-from xml.dom.minidom import parse, Attr, Node, Document, parseString
+from xml.dom.minidom import parse, Attr, Node, Document, Element, parseString
from xml.dom.minidom import getDOMImplementation
from xml.parsers.expat import ExpatError
@@ -176,6 +177,36 @@ class MinidomTest(unittest.TestCase):
self.confirm(dom.documentElement.childNodes[-1].data == "Hello")
dom.unlink()
+ @support.requires_resource('cpu')
+ def testAppendChildNoQuadraticComplexity(self):
+ impl = getDOMImplementation()
+
+ newdoc = impl.createDocument(None, "some_tag", None)
+ top_element = newdoc.documentElement
+ children = [newdoc.createElement(f"child-{i}") for i in range(1, 2 ** 15 + 1)]
+ element = top_element
+
+ start = time.monotonic()
+ for child in children:
+ element.appendChild(child)
+ element = child
+ end = time.monotonic()
+
+ # This example used to take at least 30 seconds.
+ # Conservative assertion due to the wide variety of systems and
+ # build configs timing based tests wind up run under.
+ # A --with-address-sanitizer --with-pydebug build on a rpi5 still
+ # completes this loop in <0.5 seconds.
+ self.assertLess(end - start, 4)
+
+ def testSetAttributeNodeWithoutOwnerDocument(self):
+ # regression test for gh-142754
+ elem = Element("test")
+ attr = Attr("id")
+ attr.value = "test-id"
+ elem.setAttributeNode(attr)
+ self.assertEqual(elem.getAttribute("id"), "test-id")
+
def testAppendChildFragment(self):
dom, orig, c1, c2, c3, frag = self._create_fragment_test_nodes()
dom.documentElement.appendChild(frag)
diff --git a/Lib/xml/dom/minidom.py b/Lib/xml/dom/minidom.py
index ef8a159833b..cada981f39f 100644
--- a/Lib/xml/dom/minidom.py
+++ b/Lib/xml/dom/minidom.py
@@ -292,13 +292,6 @@ def _append_child(self, node):
childNodes.append(node)
node.parentNode = self
-def _in_document(node):
- # return True iff node is part of a document tree
- while node is not None:
- if node.nodeType == Node.DOCUMENT_NODE:
- return True
- node = node.parentNode
- return False
def _write_data(writer, data):
"Writes datachars to writer."
@@ -355,6 +348,7 @@ class Attr(Node):
def __init__(self, qName, namespaceURI=EMPTY_NAMESPACE, localName=None,
prefix=None):
self.ownerElement = None
+ self.ownerDocument = None
self._name = qName
self.namespaceURI = namespaceURI
self._prefix = prefix
@@ -680,6 +674,7 @@ class Element(Node):
def __init__(self, tagName, namespaceURI=EMPTY_NAMESPACE, prefix=None,
localName=None):
+ self.ownerDocument = None
self.parentNode = None
self.tagName = self.nodeName = tagName
self.prefix = prefix
@@ -1539,7 +1534,7 @@ def _clear_id_cache(node):
if node.nodeType == Node.DOCUMENT_NODE:
node._id_cache.clear()
node._id_search_stack = None
- elif _in_document(node):
+ elif node.ownerDocument:
node.ownerDocument._id_cache.clear()
node.ownerDocument._id_search_stack= None
diff --git a/Misc/NEWS.d/next/Security/2025-12-01-09-36-45.gh-issue-142145.tcAUhg.rst b/Misc/NEWS.d/next/Security/2025-12-01-09-36-45.gh-issue-142145.tcAUhg.rst
new file mode 100644
index 00000000000..05c7df35d14
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2025-12-01-09-36-45.gh-issue-142145.tcAUhg.rst
@@ -0,0 +1,6 @@
+Remove quadratic behavior in ``xml.minidom`` node ID cache clearing. In order
+to do this without breaking existing users, we also add the *ownerDocument*
+attribute to :mod:`xml.dom.minidom` elements and attributes created by directly
+instantiating the ``Element`` or ``Attr`` class. Note that this way of creating
+nodes is not supported; creator functions like
+:py:meth:`xml.dom.Document.documentElement` should be used instead.
|
