diff options
| -rw-r--r-- | Lib/test/test_binascii.py | 28 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2018-06-05-11-29-26.bpo-33770.oBhxxw.rst | 1 | ||||
| -rw-r--r-- | Modules/binascii.c | 13 |
3 files changed, 41 insertions, 1 deletions
diff --git a/Lib/test/test_binascii.py b/Lib/test/test_binascii.py index 0997d9432b..c5fcc1ac16 100644 --- a/Lib/test/test_binascii.py +++ b/Lib/test/test_binascii.py @@ -110,6 +110,34 @@ class BinASCIITest(unittest.TestCase): # empty strings. TBD: shouldn't it raise an exception instead ? self.assertEqual(binascii.a2b_base64(self.type2test(fillers)), b'') + def test_base64errors(self): + # Test base64 with invalid padding + def assertIncorrectPadding(data): + with self.assertRaisesRegex(binascii.Error, r'(?i)Incorrect padding'): + binascii.a2b_base64(self.type2test(data)) + + assertIncorrectPadding(b'ab') + assertIncorrectPadding(b'ab=') + assertIncorrectPadding(b'abc') + assertIncorrectPadding(b'abcdef') + assertIncorrectPadding(b'abcdef=') + assertIncorrectPadding(b'abcdefg') + assertIncorrectPadding(b'a=b=') + assertIncorrectPadding(b'a\nb=') + + # Test base64 with invalid number of valid characters (1 mod 4) + def assertInvalidLength(data): + with self.assertRaisesRegex(binascii.Error, r'(?i)invalid.+length'): + binascii.a2b_base64(self.type2test(data)) + + assertInvalidLength(b'a') + assertInvalidLength(b'a=') + assertInvalidLength(b'a==') + assertInvalidLength(b'a===') + assertInvalidLength(b'a' * 5) + assertInvalidLength(b'a' * (4 * 87 + 1)) + assertInvalidLength(b'A\tB\nC ??DE') # only 5 valid characters + def test_uu(self): MAX_UU = 45 for backtick in (True, False): diff --git a/Misc/NEWS.d/next/Library/2018-06-05-11-29-26.bpo-33770.oBhxxw.rst b/Misc/NEWS.d/next/Library/2018-06-05-11-29-26.bpo-33770.oBhxxw.rst new file mode 100644 index 0000000000..a1529dda1a --- /dev/null +++ b/Misc/NEWS.d/next/Library/2018-06-05-11-29-26.bpo-33770.oBhxxw.rst @@ -0,0 +1 @@ +improve base64 exception message for encoded inputs of invalid length diff --git a/Modules/binascii.c b/Modules/binascii.c index 59e99282ae..5667018d6e 100644 --- a/Modules/binascii.c +++ b/Modules/binascii.c @@ -510,7 +510,18 @@ binascii_a2b_base64_impl(PyObject *module, Py_buffer *data) } if (leftbits != 0) { - PyErr_SetString(Error, "Incorrect padding"); + if (leftbits == 6) { + /* + ** There is exactly one extra valid, non-padding, base64 character. + ** This is an invalid length, as there is no possible input that + ** could encoded into such a base64 string. + */ + PyErr_SetString(Error, + "Invalid base64-encoded string: " + "length cannot be 1 more than a multiple of 4"); + } else { + PyErr_SetString(Error, "Incorrect padding"); + } _PyBytesWriter_Dealloc(&writer); return NULL; } |