libbinder: support TF_CLEAR_BUF

This flag instructs the kernel to clear transactions from send/reply
buffers for certain transactions which may contain sensitive data, as a
security precaution.

Bug: 171501998
Test: binderLibTest (only checks there is no error)
Change-Id: I69d732e5cc2b15472dc52d47c66716bc1b3be6ae

1 files changed, 27 insertions, 0 deletions

diff --git a/libs/binder/Utils.cpp b/libs/binder/Utils.cpp
new file mode 100644
index 0000000000..90a4502ec5
--- /dev/null
+++ b/libs/binder/Utils.cpp
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "Utils.h"
+
+#include <string.h>
+
+namespace android {
+
+void zeroMemory(uint8_t* data, size_t size) {
+    memset(data, 0, size);
+}
+
+}   // namespace android