libhwbinder: 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: hidl_test + verify by reading memory bits w/ updated kernel
Change-Id: I7dda8f8d24091f77bdaf99a7de446875356c601c

1 files changed, 27 insertions, 0 deletions

diff --git a/Utils.cpp b/Utils.cpp
new file mode 100644
index 0000000..5a29d6b
--- /dev/null
+++ b/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::hardware {
+
+void zeroMemory(uint8_t* data, size_t size) {
+    memset(data, 0, size);
+}
+
+}   // namespace android::hardware