123 lines
4.3 KiB
Diff
123 lines
4.3 KiB
Diff
From 44e458357fca05ca0ae2658d62c8c595b048b5ef Mon Sep 17 00:00:00 2001
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From: Serhiy Storchaka <storchaka@gmail.com>
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Date: Sat, 17 Aug 2024 16:30:52 +0300
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Subject: [PATCH] gh-123067: Fix quadratic complexity in parsing "-quoted
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cookie values with backslashes (GH-123075)
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This fixes CVE-2024-7592.
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---
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Lib/http/cookies.py | 34 ++------
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Lib/test/test_http_cookies.py | 38 ++++++++++
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Misc/NEWS.d/next/Library/2024-08-16-19-13-21.gh-issue-123067.Nx9O4R.rst | 1
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3 files changed, 47 insertions(+), 26 deletions(-)
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create mode 100644 Misc/NEWS.d/next/Library/2024-08-16-19-13-21.gh-issue-123067.Nx9O4R.rst
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--- a/Lib/http/cookies.py
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+++ b/Lib/http/cookies.py
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@@ -184,8 +184,13 @@ def _quote(str):
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return '"' + str.translate(_Translator) + '"'
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-_OctalPatt = re.compile(r"\\[0-3][0-7][0-7]")
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-_QuotePatt = re.compile(r"[\\].")
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+_unquote_sub = re.compile(r'\\(?:([0-3][0-7][0-7])|(.))').sub
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+
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+def _unquote_replace(m):
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+ if m[1]:
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+ return chr(int(m[1], 8))
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+ else:
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+ return m[2]
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def _unquote(str):
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# If there aren't any doublequotes,
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@@ -205,30 +210,7 @@ def _unquote(str):
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# \012 --> \n
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# \" --> "
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#
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- i = 0
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- n = len(str)
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- res = []
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- while 0 <= i < n:
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- o_match = _OctalPatt.search(str, i)
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- q_match = _QuotePatt.search(str, i)
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- if not o_match and not q_match: # Neither matched
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- res.append(str[i:])
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- break
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- # else:
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- j = k = -1
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- if o_match:
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- j = o_match.start(0)
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- if q_match:
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- k = q_match.start(0)
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- if q_match and (not o_match or k < j): # QuotePatt matched
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- res.append(str[i:k])
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- res.append(str[k+1])
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- i = k + 2
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- else: # OctalPatt matched
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- res.append(str[i:j])
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- res.append(chr(int(str[j+1:j+4], 8)))
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- i = j + 4
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- return _nulljoin(res)
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+ return _unquote_sub(_unquote_replace, str)
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# The _getdate() routine is used to set the expiration time in the cookie's HTTP
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# header. By default, _getdate() returns the current time in the appropriate
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--- a/Lib/test/test_http_cookies.py
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+++ b/Lib/test/test_http_cookies.py
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@@ -5,6 +5,7 @@ import unittest
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import doctest
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from http import cookies
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import pickle
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+from test import support
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class CookieTests(unittest.TestCase):
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@@ -58,6 +59,43 @@ class CookieTests(unittest.TestCase):
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for k, v in sorted(case['dict'].items()):
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self.assertEqual(C[k].value, v)
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+ def test_unquote(self):
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+ cases = [
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+ (r'a="b=\""', 'b="'),
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+ (r'a="b=\\"', 'b=\\'),
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+ (r'a="b=\="', 'b=='),
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+ (r'a="b=\n"', 'b=n'),
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+ (r'a="b=\042"', 'b="'),
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+ (r'a="b=\134"', 'b=\\'),
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+ (r'a="b=\377"', 'b=\xff'),
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+ (r'a="b=\400"', 'b=400'),
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+ (r'a="b=\42"', 'b=42'),
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+ (r'a="b=\\042"', 'b=\\042'),
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+ (r'a="b=\\134"', 'b=\\134'),
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+ (r'a="b=\\\""', 'b=\\"'),
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+ (r'a="b=\\\042"', 'b=\\"'),
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+ (r'a="b=\134\""', 'b=\\"'),
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+ (r'a="b=\134\042"', 'b=\\"'),
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+ ]
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+ for encoded, decoded in cases:
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+ with self.subTest(encoded):
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+ C = cookies.SimpleCookie()
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+ C.load(encoded)
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+ self.assertEqual(C['a'].value, decoded)
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+
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+ @support.requires_resource('cpu')
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+ def test_unquote_large(self):
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+ n = 10**6
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+ for encoded in r'\\', r'\134':
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+ with self.subTest(encoded):
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+ data = 'a="b=' + encoded*n + ';"'
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+ C = cookies.SimpleCookie()
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+ C.load(data)
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+ value = C['a'].value
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+ self.assertEqual(value[:3], 'b=\\')
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+ self.assertEqual(value[-2:], '\\;')
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+ self.assertEqual(len(value), n + 3)
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+
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def test_load(self):
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C = cookies.SimpleCookie()
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C.load('Customer="WILE_E_COYOTE"; Version=1; Path=/acme')
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--- /dev/null
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+++ b/Misc/NEWS.d/next/Library/2024-08-16-19-13-21.gh-issue-123067.Nx9O4R.rst
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@@ -0,0 +1 @@
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+Fix quadratic complexity in parsing ``"``-quoted cookie values with backslashes by :mod:`http.cookies`.
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