136 lines
6.1 KiB
Diff
136 lines
6.1 KiB
Diff
From 17358fb35fb7217423d4c4877ccb6d1a3a40b1c3 Mon Sep 17 00:00:00 2001
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From: Sarah Boyce <42296566+sarahboyce@users.noreply.github.com>
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Date: Wed, 26 Jun 2024 12:11:54 +0200
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Subject: [PATCH] [4.2.x] Fixed CVE-2024-39614 -- Mitigated potential DoS in
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get_supported_language_variant().
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Language codes are now parsed with a maximum length limit of 500 chars.
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Thanks to MProgrammer for the report.
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---
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django/utils/translation/trans_real.py | 25 ++++++++++++++++++++-----
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docs/ref/utils.txt | 10 ++++++++++
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tests/i18n/tests.py | 11 +++++++++++
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3 files changed, 41 insertions(+), 5 deletions(-)
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diff --git a/django/utils/translation/trans_real.py b/django/utils/translation/trans_real.py
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index 872c80b00f..ce13d1e69c 100644
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--- a/django/utils/translation/trans_real.py
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+++ b/django/utils/translation/trans_real.py
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@@ -31,9 +31,10 @@ _default = None
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CONTEXT_SEPARATOR = "\x04"
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# Maximum number of characters that will be parsed from the Accept-Language
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-# header to prevent possible denial of service or memory exhaustion attacks.
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-# About 10x longer than the longest value shown on MDN’s Accept-Language page.
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-ACCEPT_LANGUAGE_HEADER_MAX_LENGTH = 500
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+# header or cookie to prevent possible denial of service or memory exhaustion
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+# attacks. About 10x longer than the longest value shown on MDN’s
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+# Accept-Language page.
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+LANGUAGE_CODE_MAX_LENGTH = 500
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# Format of Accept-Language header values. From RFC 9110 Sections 12.4.2 and
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# 12.5.4, and RFC 5646 Section 2.1.
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@@ -497,11 +498,25 @@ def get_supported_language_variant(lang_code, strict=False):
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If `strict` is False (the default), look for a country-specific variant
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when neither the language code nor its generic variant is found.
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+ The language code is truncated to a maximum length to avoid potential
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+ denial of service attacks.
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+
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lru_cache should have a maxsize to prevent from memory exhaustion attacks,
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as the provided language codes are taken from the HTTP request. See also
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<https://www.djangoproject.com/weblog/2007/oct/26/security-fix/>.
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"""
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if lang_code:
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+ # Truncate the language code to a maximum length to avoid potential
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+ # denial of service attacks.
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+ if len(lang_code) > LANGUAGE_CODE_MAX_LENGTH:
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+ if (
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+ not strict
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+ and (index := lang_code.rfind("-", 0, LANGUAGE_CODE_MAX_LENGTH)) > 0
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+ ):
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+ # There is a generic variant under the maximum length accepted length.
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+ lang_code = lang_code[:index]
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+ else:
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+ raise ValueError("'lang_code' exceeds the maximum accepted length")
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# If 'zh-hant-tw' is not supported, try special fallback or subsequent
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# language codes i.e. 'zh-hant' and 'zh'.
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possible_lang_codes = [lang_code]
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@@ -625,13 +640,13 @@ def parse_accept_lang_header(lang_string):
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functools.lru_cache() to avoid repetitive parsing of common header values.
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"""
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# If the header value doesn't exceed the maximum allowed length, parse it.
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- if len(lang_string) <= ACCEPT_LANGUAGE_HEADER_MAX_LENGTH:
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+ if len(lang_string) <= LANGUAGE_CODE_MAX_LENGTH:
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return _parse_accept_lang_header(lang_string)
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# If there is at least one comma in the value, parse up to the last comma
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# before the max length, skipping any truncated parts at the end of the
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# header value.
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- if (index := lang_string.rfind(",", 0, ACCEPT_LANGUAGE_HEADER_MAX_LENGTH)) > 0:
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+ if (index := lang_string.rfind(",", 0, LANGUAGE_CODE_MAX_LENGTH)) > 0:
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return _parse_accept_lang_header(lang_string[:index])
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# Don't attempt to parse if there is only one language-range value which is
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diff --git a/docs/ref/utils.txt b/docs/ref/utils.txt
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index b2b826684d..471a4b31eb 100644
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--- a/docs/ref/utils.txt
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+++ b/docs/ref/utils.txt
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@@ -1155,6 +1155,11 @@ For a complete discussion on the usage of the following see the
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``lang_code`` is ``'es-ar'`` and ``'es'`` is in :setting:`LANGUAGES` but
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``'es-ar'`` isn't.
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+ ``lang_code`` has a maximum accepted length of 500 characters. A
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+ :exc:`ValueError` is raised if ``lang_code`` exceeds this limit and
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+ ``strict`` is ``True``, or if there is no generic variant and ``strict``
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+ is ``False``.
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+
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If ``strict`` is ``False`` (the default), a country-specific variant may
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be returned when neither the language code nor its generic variant is found.
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For example, if only ``'es-co'`` is in :setting:`LANGUAGES`, that's
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@@ -1163,6 +1168,11 @@ For a complete discussion on the usage of the following see the
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Raises :exc:`LookupError` if nothing is found.
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+ .. versionchanged:: 4.2.14
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+
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+ In older versions, ``lang_code`` values over 500 characters were
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+ processed without raising a :exc:`ValueError`.
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+
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.. function:: to_locale(language)
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Turns a language name (en-us) into a locale name (en_US).
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diff --git a/tests/i18n/tests.py b/tests/i18n/tests.py
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index f517c5eac7..9b029d5992 100644
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--- a/tests/i18n/tests.py
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+++ b/tests/i18n/tests.py
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@@ -65,6 +65,7 @@ from django.utils.translation.reloader import (
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translation_file_changed,
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watch_for_translation_changes,
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)
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+from django.utils.translation.trans_real import LANGUAGE_CODE_MAX_LENGTH
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from .forms import CompanyForm, I18nForm, SelectDateForm
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from .models import Company, TestModel
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@@ -1888,6 +1889,16 @@ class MiscTests(SimpleTestCase):
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g("xyz")
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with self.assertRaises(LookupError):
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g("xy-zz")
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+ msg = "'lang_code' exceeds the maximum accepted length"
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+ with self.assertRaises(LookupError):
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+ g("x" * LANGUAGE_CODE_MAX_LENGTH)
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+ with self.assertRaisesMessage(ValueError, msg):
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+ g("x" * (LANGUAGE_CODE_MAX_LENGTH + 1))
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+ # 167 * 3 = 501 which is LANGUAGE_CODE_MAX_LENGTH + 1.
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+ self.assertEqual(g("en-" * 167), "en")
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+ with self.assertRaisesMessage(ValueError, msg):
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+ g("en-" * 167, strict=True)
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+ self.assertEqual(g("en-" * 30000), "en") # catastrophic test
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def test_get_supported_language_variant_null(self):
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g = trans_null.get_supported_language_variant
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--
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2.45.2
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