Various fixes

2 files changed, 12 insertions, 7 deletions

diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index ae4b4a85..7cfdd284 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -556,8 +556,8 @@ class Backend(object):
         return self._ffi.buffer(buf)[:res]
 
     def cmac_algorithm_supported(self, algorithm):
-        return backend._lib.Cryptography_HAS_CMAC == 1 \
-            and backend.cipher_supported(algorithm, CBC(0))
+        return (backend._lib.Cryptography_HAS_CMAC == 1
+                and backend.cipher_supported(algorithm, CBC(0)))
 
     def create_cmac_ctx(self, algorithm):
         return _CMACContext(self, algorithm)
@@ -1278,6 +1278,10 @@ class _CMACContext(object):
                 )
 
             ctx = self._backend._lib.CMAC_CTX_new()
+
+            assert ctx != self._backend._ffi.NULL
+            ctx = self._backend._ffi.gc(ctx, self._backend._lib.CMAC_CTX_free)
+
             self._backend._lib.CMAC_Init(
                 ctx, self._key, len(self._key),
                 evp_cipher, self._backend._ffi.NULL
@@ -1297,14 +1301,15 @@ class _CMACContext(object):
         )
         assert res == 1
 
-        self._backend._lib.CMAC_CTX_free(self._ctx)
+        self._ctx = None
+
         return self._backend._ffi.buffer(buf)[:]
 
     def copy(self):
         copied_ctx = self._backend._lib.CMAC_CTX_new()
         self._backend._lib.CMAC_CTX_init(copied_ctx)
         copied_ctx = self._backend._ffi.gc(
-            copied_ctx, self._backend._lib.CMAC_CTX_free()
+            copied_ctx, self._backend._lib.CMAC_CTX_free
         )
         res = self._backend._lib.CMAC_CTX_copy(
             copied_ctx, self._ctx
diff --git a/cryptography/hazmat/primitives/cmac.py b/cryptography/hazmat/primitives/cmac.py
index bbf0bf9c..7e7f65ab 100644
--- a/cryptography/hazmat/primitives/cmac.py
+++ b/cryptography/hazmat/primitives/cmac.py
@@ -36,11 +36,11 @@ class CMAC(object):
             raise TypeError(
                 "Expected instance of interfaces.BlockCipherAlgorithm"
             )
-        self.algorithm = algorithm
+        self._algorithm = algorithm
 
         self._backend = backend
         if ctx is None:
-            self._ctx = self._backend.create_cmac_ctx(self.algorithm)
+            self._ctx = self._backend.create_cmac_ctx(self._algorithm)
         else:
             self._ctx = ctx
 
@@ -69,7 +69,7 @@ class CMAC(object):
         if self._ctx is None:
             raise AlreadyFinalized("Context was already finalized")
         return CMAC(
-            self.algorithm,
+            self._algorithm,
             backend=self._backend,
             ctx=self._ctx.copy()
         )