[Python-checkins] cpython (2.7): add a default limit for the amount of data xmlrpclib.gzip_decode will return
benjamin.peterson
python-checkins at python.org
Sat Dec 6 02:17:00 CET 2014
https://hg.python.org/cpython/rev/d50096708b2d
changeset: 93748:d50096708b2d
branch: 2.7
user: Benjamin Peterson <benjamin at python.org>
date: Fri Dec 05 20:15:15 2014 -0500
summary:
add a default limit for the amount of data xmlrpclib.gzip_decode will return (closes #16043)
files:
Lib/test/test_xmlrpc.py | 19 ++++++++++++++++++-
Lib/xmlrpclib.py | 13 +++++++++++--
Misc/NEWS | 3 +++
3 files changed, 32 insertions(+), 3 deletions(-)
diff --git a/Lib/test/test_xmlrpc.py b/Lib/test/test_xmlrpc.py
--- a/Lib/test/test_xmlrpc.py
+++ b/Lib/test/test_xmlrpc.py
@@ -737,7 +737,7 @@
with cm:
p.pow(6, 8)
- def test_gsip_response(self):
+ def test_gzip_response(self):
t = self.Transport()
p = xmlrpclib.ServerProxy(URL, transport=t)
old = self.requestHandler.encode_threshold
@@ -750,6 +750,23 @@
self.requestHandler.encode_threshold = old
self.assertTrue(a>b)
+ def test_gzip_decode_limit(self):
+ max_gzip_decode = 20 * 1024 * 1024
+ data = '\0' * max_gzip_decode
+ encoded = xmlrpclib.gzip_encode(data)
+ decoded = xmlrpclib.gzip_decode(encoded)
+ self.assertEqual(len(decoded), max_gzip_decode)
+
+ data = '\0' * (max_gzip_decode + 1)
+ encoded = xmlrpclib.gzip_encode(data)
+
+ with self.assertRaisesRegexp(ValueError,
+ "max gzipped payload length exceeded"):
+ xmlrpclib.gzip_decode(encoded)
+
+ xmlrpclib.gzip_decode(encoded, max_decode=-1)
+
+
#Test special attributes of the ServerProxy object
class ServerProxyTestCase(unittest.TestCase):
def setUp(self):
diff --git a/Lib/xmlrpclib.py b/Lib/xmlrpclib.py
--- a/Lib/xmlrpclib.py
+++ b/Lib/xmlrpclib.py
@@ -49,6 +49,7 @@
# 2003-07-12 gp Correct marshalling of Faults
# 2003-10-31 mvl Add multicall support
# 2004-08-20 mvl Bump minimum supported Python version to 2.1
+# 2014-12-02 ch/doko Add workaround for gzip bomb vulnerability
#
# Copyright (c) 1999-2002 by Secret Labs AB.
# Copyright (c) 1999-2002 by Fredrik Lundh.
@@ -1165,10 +1166,13 @@
# in the HTTP header, as described in RFC 1952
#
# @param data The encoded data
+# @keyparam max_decode Maximum bytes to decode (20MB default), use negative
+# values for unlimited decoding
# @return the unencoded data
# @raises ValueError if data is not correctly coded.
+# @raises ValueError if max gzipped payload length exceeded
-def gzip_decode(data):
+def gzip_decode(data, max_decode=20971520):
"""gzip encoded data -> unencoded data
Decode data using the gzip content encoding as described in RFC 1952
@@ -1178,11 +1182,16 @@
f = StringIO.StringIO(data)
gzf = gzip.GzipFile(mode="rb", fileobj=f)
try:
- decoded = gzf.read()
+ if max_decode < 0: # no limit
+ decoded = gzf.read()
+ else:
+ decoded = gzf.read(max_decode + 1)
except IOError:
raise ValueError("invalid data")
f.close()
gzf.close()
+ if max_decode >= 0 and len(decoded) > max_decode:
+ raise ValueError("max gzipped payload length exceeded")
return decoded
##
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
Library
-------
+- Issue #16043: Add a default limit for the amount of data xmlrpclib.gzip_decode
+ will return. This resolves CVE-2013-1753.
+
- Issue #16042: CVE-2013-1752: smtplib: Limit amount of data read by limiting
the call to readline(). Original patch by Christian Heimes.
--
Repository URL: https://hg.python.org/cpython
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