43 lines
1.8 KiB
Diff
43 lines
1.8 KiB
Diff
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From 1fa6ef2bc7cee1c8e088dd8b397d9b2d54036dbc Mon Sep 17 00:00:00 2001
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From: Rajarishi Devarajan <rishi93dev@gmail.com>
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Date: Sun, 12 Jul 2020 23:47:42 +0200
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Subject: [PATCH 1/4] bpo-39017 Fix infinite loop in the tarfile module
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Add a check for length = 0 in the _proc_pax function to avoid running into an infinite loop
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---
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Lib/tarfile.py | 2 ++
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Lib/test/test_tarfile.py | 5 +++++
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Misc/NEWS.d/next/Library/2020-07-12-22-16-58.bpo-39017.x3Cg-9.rst | 1 +
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3 files changed, 8 insertions(+)
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create mode 100644 Lib/test/recursion.tar
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--- a/Lib/tarfile.py
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+++ b/Lib/tarfile.py
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@@ -1400,6 +1400,8 @@ class TarInfo(object):
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length, keyword = match.groups()
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length = int(length)
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+ if length == 0:
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+ raise InvalidHeaderError("invalid header")
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value = buf[match.end(2) + 1:match.start(1) + length - 1]
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keyword = keyword.decode("utf8")
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--- a/Lib/test/test_tarfile.py
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+++ b/Lib/test/test_tarfile.py
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@@ -321,6 +321,11 @@ class CommonReadTest(ReadTest):
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with self.assertRaisesRegexp(tarfile.ReadError, "unexpected end of data"):
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tar.extractfile(t).read()
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+ def test_length_zero_header(self):
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+ # bpo-39017 (CVE-2019-20907): reading a zero-length header should fail
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+ # with an exception
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+ self.assertRaises(tarfile.ReadError, tarfile.open, test_support.findfile('recursion.tar'))
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+
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class MiscReadTest(CommonReadTest):
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taropen = tarfile.TarFile.taropen
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--- /dev/null
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+++ b/Misc/NEWS.d/next/Library/2020-07-12-22-16-58.bpo-39017.x3Cg-9.rst
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@@ -0,0 +1 @@
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+Avoid infinite loop when reading specially crafted TAR files using the tarfile module (CVE-2019-20907).
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