diff options
| -rw-r--r-- | Lib/encodings/idna.py | 32 | ||||
| -rw-r--r-- | Lib/test/test_codecs.py | 6 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Security/2022-11-04-09-29-36.gh-issue-98433.l76c5G.rst | 6 |
3 files changed, 27 insertions, 17 deletions
diff --git a/Lib/encodings/idna.py b/Lib/encodings/idna.py index ea4058512fe..bf98f513366 100644 --- a/Lib/encodings/idna.py +++ b/Lib/encodings/idna.py @@ -39,23 +39,21 @@ def nameprep(label): # Check bidi RandAL = [stringprep.in_table_d1(x) for x in label] - for c in RandAL: - if c: - # There is a RandAL char in the string. Must perform further - # tests: - # 1) The characters in section 5.8 MUST be prohibited. - # This is table C.8, which was already checked - # 2) If a string contains any RandALCat character, the string - # MUST NOT contain any LCat character. - if any(stringprep.in_table_d2(x) for x in label): - raise UnicodeError("Violation of BIDI requirement 2") - - # 3) If a string contains any RandALCat character, a - # RandALCat character MUST be the first character of the - # string, and a RandALCat character MUST be the last - # character of the string. - if not RandAL[0] or not RandAL[-1]: - raise UnicodeError("Violation of BIDI requirement 3") + if any(RandAL): + # There is a RandAL char in the string. Must perform further + # tests: + # 1) The characters in section 5.8 MUST be prohibited. + # This is table C.8, which was already checked + # 2) If a string contains any RandALCat character, the string + # MUST NOT contain any LCat character. + if any(stringprep.in_table_d2(x) for x in label): + raise UnicodeError("Violation of BIDI requirement 2") + # 3) If a string contains any RandALCat character, a + # RandALCat character MUST be the first character of the + # string, and a RandALCat character MUST be the last + # character of the string. + if not RandAL[0] or not RandAL[-1]: + raise UnicodeError("Violation of BIDI requirement 3") return label diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py index 42c600dcb00..87bd8202995 100644 --- a/Lib/test/test_codecs.py +++ b/Lib/test/test_codecs.py @@ -1552,6 +1552,12 @@ class IDNACodecTest(unittest.TestCase): self.assertEqual("pyth\xf6n.org".encode("idna"), b"xn--pythn-mua.org") self.assertEqual("pyth\xf6n.org.".encode("idna"), b"xn--pythn-mua.org.") + def test_builtin_decode_length_limit(self): + with self.assertRaisesRegex(UnicodeError, "too long"): + (b"xn--016c"+b"a"*1100).decode("idna") + with self.assertRaisesRegex(UnicodeError, "too long"): + (b"xn--016c"+b"a"*70).decode("idna") + def test_stream(self): r = codecs.getreader("idna")(io.BytesIO(b"abc")) r.read(3) diff --git a/Misc/NEWS.d/next/Security/2022-11-04-09-29-36.gh-issue-98433.l76c5G.rst b/Misc/NEWS.d/next/Security/2022-11-04-09-29-36.gh-issue-98433.l76c5G.rst new file mode 100644 index 00000000000..5185fac2e29 --- /dev/null +++ b/Misc/NEWS.d/next/Security/2022-11-04-09-29-36.gh-issue-98433.l76c5G.rst @@ -0,0 +1,6 @@ +The IDNA codec decoder used on DNS hostnames by :mod:`socket` or :mod:`asyncio` +related name resolution functions no longer involves a quadratic algorithm. +This prevents a potential CPU denial of service if an out-of-spec excessive +length hostname involving bidirectional characters were decoded. Some protocols +such as :mod:`urllib` http ``3xx`` redirects potentially allow for an attacker +to supply such a name. |