1 files changed, 67 insertions, 0 deletions
diff --git a/thirdparty/mbedtls/library/platform_util.c b/thirdparty/mbedtls/library/platform_util.c
new file mode 100644
index 0000000000..1a57de9393
--- /dev/null
+++ b/thirdparty/mbedtls/library/platform_util.c
@@ -0,0 +1,67 @@
+/*
+ * Common and shared functions used by multiple modules in the Mbed TLS
+ * library.
+ *
+ *  Copyright (C) 2018, Arm Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of Mbed TLS (https://tls.mbed.org)
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#include "mbedtls/platform_util.h"
+
+#include <stddef.h>
+#include <string.h>
+
+#if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT)
+/*
+ * This implementation should never be optimized out by the compiler
+ *
+ * This implementation for mbedtls_platform_zeroize() was inspired from Colin
+ * Percival's blog article at:
+ *
+ * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
+ *
+ * It uses a volatile function pointer to the standard memset(). Because the
+ * pointer is volatile the compiler expects it to change at
+ * any time and will not optimize out the call that could potentially perform
+ * other operations on the input buffer instead of just setting it to 0.
+ * Nevertheless, as pointed out by davidtgoldblatt on Hacker News
+ * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for
+ * details), optimizations of the following form are still possible:
+ *
+ * if( memset_func != memset )
+ *     memset_func( buf, 0, len );
+ *
+ * Note that it is extremely difficult to guarantee that
+ * mbedtls_platform_zeroize() will not be optimized out by aggressive compilers
+ * in a portable way. For this reason, Mbed TLS also provides the configuration
+ * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
+ * mbedtls_platform_zeroize() to use a suitable implementation for their
+ * platform and needs.
+ */
+static void * (* const volatile memset_func)( void *, int, size_t ) = memset;
+
+void mbedtls_platform_zeroize( void *buf, size_t len )
+{
+    memset_func( buf, 0, len );
+}
+#endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */