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From 9fbf84efc861668755ab645530ec7be9cf3c6696 Mon Sep 17 00:00:00 2001
From: Alex Gaynor <alex.gaynor@gmail.com>
Date: Tue, 7 Feb 2023 11:34:18 -0500
Subject: [PATCH] Don't allow update_into to mutate immutable objects (#8230)
Upstream-Status: Backport [https://github.com/pyca/cryptography/commit/9fbf84efc861668755ab645530ec7be9cf3c6696]
CVE: CVE-2023-23931
Signed-off-by: Vijay Anusuri <vanusuri@mvista.com>
---
src/cryptography/hazmat/backends/openssl/ciphers.py | 2 +-
tests/hazmat/primitives/test_ciphers.py | 8 ++++++++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/src/cryptography/hazmat/backends/openssl/ciphers.py b/src/cryptography/hazmat/backends/openssl/ciphers.py
index 286583f9325..075d68fb905 100644
--- a/src/cryptography/hazmat/backends/openssl/ciphers.py
+++ b/src/cryptography/hazmat/backends/openssl/ciphers.py
@@ -156,7 +156,7 @@ def update_into(self, data: bytes, buf: bytes) -> int:
data_processed = 0
total_out = 0
outlen = self._backend._ffi.new("int *")
- baseoutbuf = self._backend._ffi.from_buffer(buf)
+ baseoutbuf = self._backend._ffi.from_buffer(buf, require_writable=True)
baseinbuf = self._backend._ffi.from_buffer(data)
while data_processed != total_data_len:
diff --git a/tests/hazmat/primitives/test_ciphers.py b/tests/hazmat/primitives/test_ciphers.py
index 02127dd9cab..bf3b047dec2 100644
--- a/tests/hazmat/primitives/test_ciphers.py
+++ b/tests/hazmat/primitives/test_ciphers.py
@@ -318,6 +318,14 @@ def test_update_into_buffer_too_small(self, backend):
with pytest.raises(ValueError):
encryptor.update_into(b"testing", buf)
+ def test_update_into_immutable(self, backend):
+ key = b"\x00" * 16
+ c = ciphers.Cipher(AES(key), modes.ECB(), backend)
+ encryptor = c.encryptor()
+ buf = b"\x00" * 32
+ with pytest.raises((TypeError, BufferError)):
+ encryptor.update_into(b"testing", buf)
+
@pytest.mark.supported(
only_if=lambda backend: backend.cipher_supported(
AES(b"\x00" * 16), modes.GCM(b"\x00" * 12)
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