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From 7c72190620c3ccaeeab53fdd93547ca4d37b2f6b Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 25 Oct 2020 06:15:18 -0700
Subject: [PATCH] chunking didn't actually work (#5499)
Upstream-Status: Backport [https://github.com/pyca/cryptography/commit/836a92a28fbe9df8c37121e340b91ed9cd519ddd]
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
---
src/cryptography/hazmat/backends/openssl/ciphers.py | 2 +-
tests/hazmat/primitives/test_ciphers.py | 9 +++++++++
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/src/cryptography/hazmat/backends/openssl/ciphers.py b/src/cryptography/hazmat/backends/openssl/ciphers.py
index 86bc94b3..2b7da80c 100644
--- a/src/cryptography/hazmat/backends/openssl/ciphers.py
+++ b/src/cryptography/hazmat/backends/openssl/ciphers.py
@@ -17,7 +17,7 @@ from cryptography.hazmat.primitives.ciphers import modes
class _CipherContext(object):
_ENCRYPT = 1
_DECRYPT = 0
- _MAX_CHUNK_SIZE = 2 ** 31
+ _MAX_CHUNK_SIZE = 2 ** 31 - 1
def __init__(self, backend, cipher, mode, operation):
self._backend = backend
diff --git a/tests/hazmat/primitives/test_ciphers.py b/tests/hazmat/primitives/test_ciphers.py
index b88610e7..fd9048b7 100644
--- a/tests/hazmat/primitives/test_ciphers.py
+++ b/tests/hazmat/primitives/test_ciphers.py
@@ -326,3 +326,12 @@ class TestCipherUpdateInto(object):
decbuf = bytearray(527)
decprocessed = decryptor.update_into(buf[:processed], decbuf)
assert decbuf[:decprocessed] == pt
+
+ def test_max_chunk_size_fits_in_int32(self, backend):
+ # max chunk must fit in signed int32 or else a call large enough to
+ # cause chunking will result in the very OverflowError we want to
+ # avoid with chunking.
+ key = b"\x00" * 16
+ c = ciphers.Cipher(AES(key), modes.ECB(), backend)
+ encryptor = c.encryptor()
+ backend._ffi.new("int *", encryptor._ctx._MAX_CHUNK_SIZE)
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