Do not memlock test_key in LUKS2_check_cipher.

It's the test key only used to verify if the cipher
can be properly initialized with provided key size
parameter.

Also do not force erase of test buffer, it contains
encrypted zeroes.

Author: oniko

lib/luks2/luks2_luks1_convert.c

@@ -23,7 +23,7 @@ int LUKS2_check_cipher(struct crypt_device *cd,
 
 	log_dbg(cd, "Checking if cipher %s-%s is usable (storage wrapper).", cipher, cipher_mode);
 
-	empty_key = crypt_safe_alloc(keylength);
+	empty_key = malloc(keylength);
 	if (!empty_key)
 		return -ENOMEM;
 
@@ -40,8 +40,7 @@ int LUKS2_check_cipher(struct crypt_device *cd,
 	r = crypt_storage_decrypt(s, 0, sizeof(buf), buf);
 	crypt_storage_destroy(s);
 out:
-	crypt_safe_free(empty_key);
-	crypt_safe_memzero(buf, sizeof(buf));
+	free(empty_key);
 	return r;
 }