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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Lumir Balhar <lbalhar@redhat.com>
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Date: Fri, 17 Sep 2021 07:56:50 +0200
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Subject: [PATCH] 00368-CVE-2021-3737.patch
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00368 #
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CVE-2021-3737: http client infinite line reading (DoS) after a HTTP 100 Continue
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Fixes http.client potential denial of service where it could get stuck reading
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lines from a malicious server after a 100 Continue response.
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Backported from Python 3.
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Co-authored-by: Gregory P. Smith <greg@krypto.org>
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Co-authored-by: Gen Xu <xgbarry@gmail.com>
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---
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Lib/httplib.py | 32 +++++++++++++++++++++++---------
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Lib/test/test_httplib.py | 8 ++++++++
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2 files changed, 31 insertions(+), 9 deletions(-)
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diff --git a/Lib/httplib.py b/Lib/httplib.py
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index a63677477d5..f9a27619e62 100644
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--- a/Lib/httplib.py
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+++ b/Lib/httplib.py
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@@ -365,6 +365,25 @@ class HTTPMessage(mimetools.Message):
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# It's not a header line; skip it and try the next line.
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self.status = 'Non-header line where header expected'
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+
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+def _read_headers(fp):
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+ """Reads potential header lines into a list from a file pointer.
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+ Length of line is limited by _MAXLINE, and number of
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+ headers is limited by _MAXHEADERS.
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+ """
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+ headers = []
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+ while True:
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+ line = fp.readline(_MAXLINE + 1)
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+ if len(line) > _MAXLINE:
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+ raise LineTooLong("header line")
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+ headers.append(line)
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+ if len(headers) > _MAXHEADERS:
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+ raise HTTPException("got more than %d headers" % _MAXHEADERS)
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+ if line in (b'\r\n', b'\n', b''):
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+ break
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+ return headers
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+
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+
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class HTTPResponse:
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# strict: If true, raise BadStatusLine if the status line can't be
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@@ -453,15 +472,10 @@ class HTTPResponse:
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if status != CONTINUE:
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break
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# skip the header from the 100 response
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- while True:
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- skip = self.fp.readline(_MAXLINE + 1)
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- if len(skip) > _MAXLINE:
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- raise LineTooLong("header line")
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- skip = skip.strip()
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- if not skip:
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- break
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- if self.debuglevel > 0:
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- print "header:", skip
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+ skipped_headers = _read_headers(self.fp)
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+ if self.debuglevel > 0:
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+ print("headers:", skipped_headers)
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+ del skipped_headers
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self.status = status
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self.reason = reason.strip()
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diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
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index b5fec9aa1ec..d05c0fc28d2 100644
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--- a/Lib/test/test_httplib.py
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+++ b/Lib/test/test_httplib.py
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@@ -700,6 +700,14 @@ class BasicTest(TestCase):
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resp = httplib.HTTPResponse(FakeSocket(body))
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self.assertRaises(httplib.LineTooLong, resp.begin)
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+ def test_overflowing_header_limit_after_100(self):
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+ body = (
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+ 'HTTP/1.1 100 OK\r\n'
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+ 'r\n' * 32768
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+ )
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+ resp = httplib.HTTPResponse(FakeSocket(body))
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+ self.assertRaises(httplib.HTTPException, resp.begin)
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+
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def test_overflowing_chunked_line(self):
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body = (
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'HTTP/1.1 200 OK\r\n'
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