python3-django: Fix CVE-2023-23969

In Django 3.2 before 3.2.17, 4.0 before 4.0.9, and 4.1 before 4.1.6, the parsed values
of Accept-Language headers are cached in order to avoid repetitive parsing. This leads
to a potential denial-of-service vector via excessive memory usage if the raw value of
Accept-Language headers is very large.

References:
https://nvd.nist.gov/vuln/detail/CVE-2023-23969

Upstream-patch:
https://github.com/django/django/commit/c7e0151fdf33e1b11d488b6f67b94fdf3a30614a

Signed-off-by: Soumya Sambu <soumya.sambu@windriver.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

1 files changed, 108 insertions, 0 deletions

diff --git a/meta-python/recipes-devtools/python/python3-django/CVE-2023-23969.patch b/meta-python/recipes-devtools/python/python3-django/CVE-2023-23969.patch
new file mode 100644
index 0000000000..42e25ad3be
--- /dev/null
+++ b/meta-python/recipes-devtools/python/python3-django/CVE-2023-23969.patch
@@ -0,0 +1,108 @@
+From c7e0151fdf33e1b11d488b6f67b94fdf3a30614a Mon Sep 17 00:00:00 2001
+From: Nick Pope <nick@nickpope.me.uk>
+Date: Wed, 25 Jan 2023 12:21:48 +0100
+Subject: [PATCH] [3.2.x] Fixed CVE-2023-23969 -- Prevented DoS with
+ pathological values for Accept-Language.
+
+The parsed values of Accept-Language headers are cached in order to
+avoid repetitive parsing. This leads to a potential denial-of-service
+vector via excessive memory usage if the raw value of Accept-Language
+headers is very large.
+
+Accept-Language headers are now limited to a maximum length in order
+to avoid this issue.
+
+CVE: CVE-2023-23969
+
+Upstream-Status: Backport [https://github.com/django/django/commit/c7e0151fdf33e1b11d488b6f67b94fdf3a30614a]
+
+Signed-off-by: Soumya Sambu <soumya.sambu@windriver.com>
+---
+ django/utils/translation/trans_real.py | 30 +++++++++++++++++++++++++-
+ tests/i18n/tests.py                    | 12 +++++++++++
+ 2 files changed, 41 insertions(+), 1 deletion(-)
+
+diff --git a/django/utils/translation/trans_real.py b/django/utils/translation/trans_real.py
+index 486b2b2..7f658cf 100644
+--- a/django/utils/translation/trans_real.py
++++ b/django/utils/translation/trans_real.py
+@@ -29,6 +29,10 @@ _default = None
+ # magic gettext number to separate context from message
+ CONTEXT_SEPARATOR = "\x04"
+
++# Maximum number of characters that will be parsed from the Accept-Language
++# header to prevent possible denial of service or memory exhaustion attacks.
++ACCEPT_LANGUAGE_HEADER_MAX_LENGTH = 500
++
+ # Format of Accept-Language header values. From RFC 2616, section 14.4 and 3.9
+ # and RFC 3066, section 2.1
+ accept_language_re = re.compile(r'''
+@@ -560,7 +564,7 @@ def get_language_from_request(request, check_path=False):
+
+
+ @functools.lru_cache(maxsize=1000)
+-def parse_accept_lang_header(lang_string):
++def _parse_accept_lang_header(lang_string):
+     """
+     Parse the lang_string, which is the body of an HTTP Accept-Language
+     header, and return a tuple of (lang, q-value), ordered by 'q' values.
+@@ -582,3 +586,27 @@ def parse_accept_lang_header(lang_string):
+         result.append((lang, priority))
+     result.sort(key=lambda k: k[1], reverse=True)
+     return tuple(result)
++
++
++def parse_accept_lang_header(lang_string):
++    """
++    Parse the value of the Accept-Language header up to a maximum length.
++
++    The value of the header is truncated to a maximum length to avoid potential
++    denial of service and memory exhaustion attacks. Excessive memory could be
++    used if the raw value is very large as it would be cached due to the use of
++    `functools.lru_cache()` to avoid repetitive parsing of common header values.
++    """
++    # If the header value doesn't exceed the maximum allowed length, parse it.
++    if len(lang_string) <= ACCEPT_LANGUAGE_HEADER_MAX_LENGTH:
++        return _parse_accept_lang_header(lang_string)
++
++    # If there is at least one comma in the value, parse up to the last comma,
++    # skipping any truncated parts at the end of the header value.
++    index = lang_string.rfind(",", 0, ACCEPT_LANGUAGE_HEADER_MAX_LENGTH)
++    if index > 0:
++        return _parse_accept_lang_header(lang_string[:index])
++
++    # Don't attempt to parse if there is only one language-range value which is
++    # longer than the maximum allowed length and so truncated.
++    return ()
+diff --git a/tests/i18n/tests.py b/tests/i18n/tests.py
+index 7381cb9..6efc3a5 100644
+--- a/tests/i18n/tests.py
++++ b/tests/i18n/tests.py
+@@ -1282,6 +1282,14 @@ class MiscTests(SimpleTestCase):
+             ('de;q=0.', [('de', 0.0)]),
+             ('en; q=1,', [('en', 1.0)]),
+             ('en; q=1.0, * ; q=0.5', [('en', 1.0), ('*', 0.5)]),
++            (
++                'en' + '-x' * 20,
++                [('en-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x', 1.0)],
++            ),
++            (
++                ', '.join(['en; q=1.0'] * 20),
++                [('en', 1.0)] * 20,
++            ),
+             # Bad headers
+             ('en-gb;q=1.0000', []),
+             ('en;q=0.1234', []),
+@@ -1297,6 +1305,10 @@ class MiscTests(SimpleTestCase):
+             ('12-345', []),
+             ('', []),
+             ('en;q=1e0', []),
++            # Invalid as language-range value too long.
++            ('xxxxxxxx' + '-xxxxxxxx' * 500, []),
++            # Header value too long, only parse up to limit.
++            (', '.join(['en; q=1.0'] * 500), [('en', 1.0)] * 45),
+         ]
+         for value, expected in tests:
+             with self.subTest(value=value):
+--
+2.40.0