101 lines
4.3 KiB
Diff
101 lines
4.3 KiB
Diff
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From ffde9b888863f30c62c728c6f9538a09d7396ed9 Mon Sep 17 00:00:00 2001
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From: starlet-dx <15929766099@163.com>
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Date: Mon, 13 Feb 2023 19:26:27 +0800
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Subject: [PATCH 1/1] [4.1.x] Fixed CVE-2023-23969 -- Prevented DoS with pathological values for Accept-Language.
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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.
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Accept-Language headers are now limited to a maximum length in order to
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avoid this issue.
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---
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django/utils/translation/trans_real.py | 31 +++++++++++++++++++++++++-
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tests/i18n/tests.py | 12 ++++++++++
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2 files changed, 42 insertions(+), 1 deletion(-)
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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 423f30e..2974cc6 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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@@ -30,6 +30,11 @@ _default = None
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# magic gettext number to separate context from message
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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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+
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# Format of Accept-Language header values. From RFC 2616, section 14.4 and 3.9
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# and RFC 3066, section 2.1
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accept_language_re = _lazy_re_compile(
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@@ -586,7 +591,7 @@ def get_language_from_request(request, check_path=False):
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@functools.lru_cache(maxsize=1000)
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-def parse_accept_lang_header(lang_string):
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+def _parse_accept_lang_header(lang_string):
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"""
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Parse the lang_string, which is the body of an HTTP Accept-Language
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header, and return a tuple of (lang, q-value), ordered by 'q' values.
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@@ -608,3 +613,27 @@ def parse_accept_lang_header(lang_string):
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result.append((lang, priority))
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result.sort(key=lambda k: k[1], reverse=True)
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return tuple(result)
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+
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+
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+def parse_accept_lang_header(lang_string):
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+ """
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+ Parse the value of the Accept-Language header up to a maximum length.
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+
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+ The value of the header is truncated to a maximum length to avoid potential
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+ denial of service and memory exhaustion attacks. Excessive memory could be
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+ used if the raw value is very large as it would be cached due to the use of
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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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+ return _parse_accept_lang_header(lang_string)
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+
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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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+ return _parse_accept_lang_header(lang_string[:index])
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+
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+ # Don't attempt to parse if there is only one language-range value which is
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+ # longer than the maximum allowed length and so truncated.
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+ return ()
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diff --git a/tests/i18n/tests.py b/tests/i18n/tests.py
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index 40fc306..b361a84 100644
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--- a/tests/i18n/tests.py
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+++ b/tests/i18n/tests.py
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@@ -1730,6 +1730,14 @@ class MiscTests(SimpleTestCase):
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("de;q=0.", [("de", 0.0)]),
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("en; q=1,", [("en", 1.0)]),
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("en; q=1.0, * ; q=0.5", [("en", 1.0), ("*", 0.5)]),
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+ (
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+ "en" + "-x" * 20,
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+ [("en-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x", 1.0)],
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+ ),
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+ (
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+ ", ".join(["en; q=1.0"] * 20),
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+ [("en", 1.0)] * 20,
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+ ),
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# Bad headers
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("en-gb;q=1.0000", []),
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("en;q=0.1234", []),
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@@ -1746,6 +1754,10 @@ class MiscTests(SimpleTestCase):
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("", []),
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("en;q=1e0", []),
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("en-au;q=１.０", []),
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+ # Invalid as language-range value too long.
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+ ("xxxxxxxx" + "-xxxxxxxx" * 500, []),
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+ # Header value too long, only parse up to limit.
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+ (", ".join(["en; q=1.0"] * 500), [("en", 1.0)] * 45),
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]
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for value, expected in tests:
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with self.subTest(value=value):
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--
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2.30.0
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