Raise padding block_size limit to what is allowed by the specs. (#3108)

* Raize padding block_size limit to what is allowed by the specs.

* Add tests for raising padding limits.

* Amend C code for padding check to use uint16_t instead of uint8_t.

* Fix test to work in Python 3.

* Fix typo.

* Fix another typo.

* Fix return type of the padding checks.

* Change hypothesis test on padding.

* Update comment.

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/hazmat/primitives/test_padding.py b/tests/hazmat/primitives/test_padding.py
index e934c0ac..fb72a794 100644
--- a/tests/hazmat/primitives/test_padding.py
+++ b/tests/hazmat/primitives/test_padding.py
@@ -6,6 +6,8 @@ from __future__ import absolute_import, division, print_function
 
 import pytest
 
+import six
+
 from cryptography.exceptions import AlreadyFinalized
 from cryptography.hazmat.primitives import padding
 
@@ -100,6 +102,20 @@ class TestPKCS7(object):
         with pytest.raises(AlreadyFinalized):
             unpadder.finalize()
 
+    def test_large_padding(self):
+        padder = padding.PKCS7(2040).padder()
+        padded_data = padder.update(b"")
+        padded_data += padder.finalize()
+
+        for i in six.iterbytes(padded_data):
+            assert i == 255
+
+        unpadder = padding.PKCS7(2040).unpadder()
+        data = unpadder.update(padded_data)
+        data += unpadder.finalize()
+
+        assert data == b""
+
 
 class TestANSIX923(object):
     @pytest.mark.parametrize("size", [127, 4096, -2])