diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn index 0b8e9ae0e9..c665e03914 100644 --- a/rtc_base/BUILD.gn +++ b/rtc_base/BUILD.gn @@ -549,6 +549,7 @@ rtc_static_library("rtc_base_generic") { ":checks", ":stringutils", "..:webrtc_common", + "../api:array_view", "../api:optional", ] public_deps = [ @@ -655,6 +656,8 @@ rtc_static_library("rtc_base_generic") { "stream.h", "thread.cc", "thread.h", + "zero_memory.cc", + "zero_memory.h", ] visibility = [ @@ -1090,6 +1093,7 @@ if (rtc_include_tests) { "stream_unittest.cc", "testclient_unittest.cc", "thread_unittest.cc", + "zero_memory_unittest.cc", ] if (is_win) { sources += [ @@ -1110,6 +1114,7 @@ if (rtc_include_tests) { ":rtc_base_tests_main", ":rtc_base_tests_utils", ":stringutils", + "../api:array_view", "../api:optional", "../test:test_support", ] diff --git a/rtc_base/zero_memory.cc b/rtc_base/zero_memory.cc new file mode 100644 index 0000000000..63600b8d2e --- /dev/null +++ b/rtc_base/zero_memory.cc @@ -0,0 +1,36 @@ +/* + * Copyright 2017 The WebRTC Project Authors. All rights reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#if defined(WEBRTC_WIN) +#include +#else +#include +#endif + +#include "rtc_base/checks.h" +#include "rtc_base/zero_memory.h" + +namespace rtc { + +// Code and comment taken from "OPENSSL_cleanse" of BoringSSL. +void ExplicitZeroMemory(void* ptr, size_t len) { + RTC_DCHECK(ptr || !len); +#if defined(WEBRTC_WIN) + SecureZeroMemory(ptr, len); +#else + memset(ptr, 0, len); + /* As best as we can tell, this is sufficient to break any optimisations that + might try to eliminate "superfluous" memsets. If there's an easy way to + detect memset_s, it would be better to use that. */ + __asm__ __volatile__("" : : "r"(ptr) : "memory"); // NOLINT +#endif +} + +} // namespace rtc diff --git a/rtc_base/zero_memory.h b/rtc_base/zero_memory.h new file mode 100644 index 0000000000..cb4646c1fe --- /dev/null +++ b/rtc_base/zero_memory.h @@ -0,0 +1,33 @@ +/* + * Copyright 2017 The WebRTC Project Authors. All rights reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#ifndef RTC_BASE_ZERO_MEMORY_H_ +#define RTC_BASE_ZERO_MEMORY_H_ + +#include + +#include "api/array_view.h" + +namespace rtc { + +// Fill memory with zeros in a way that the compiler doesn't optimize it away +// even if the pointer is not used afterwards. +void ExplicitZeroMemory(void* ptr, size_t len); + +template ::value && + std::is_trivial::value>::type* = nullptr> +void ExplicitZeroMemory(rtc::ArrayView a) { + ExplicitZeroMemory(a.data(), a.size()); +} + +} // namespace rtc + +#endif // RTC_BASE_ZERO_MEMORY_H_ diff --git a/rtc_base/zero_memory_unittest.cc b/rtc_base/zero_memory_unittest.cc new file mode 100644 index 0000000000..0f496705e7 --- /dev/null +++ b/rtc_base/zero_memory_unittest.cc @@ -0,0 +1,52 @@ +/* + * Copyright 2017 The WebRTC Project Authors. All rights reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#include "rtc_base/zero_memory.h" + +#include "api/array_view.h" +#include "rtc_base/buffer.h" +#include "rtc_base/gunit.h" + +namespace rtc { + +TEST(ZeroMemoryTest, TestZeroMemory) { + static const size_t kBufferSize = 32; + uint8_t buffer[kBufferSize]; + for (size_t i = 0; i < kBufferSize; i++) { + buffer[i] = static_cast(i + 1); + } + ExplicitZeroMemory(buffer, sizeof(buffer)); + for (size_t i = 0; i < kBufferSize; i++) { + EXPECT_EQ(buffer[i], 0); + } +} + +TEST(ZeroMemoryTest, TestZeroArrayView) { + static const size_t kBufferSize = 32; + uint8_t buffer[kBufferSize]; + for (size_t i = 0; i < kBufferSize; i++) { + buffer[i] = static_cast(i + 1); + } + ExplicitZeroMemory(rtc::ArrayView(buffer, sizeof(buffer))); + for (size_t i = 0; i < kBufferSize; i++) { + EXPECT_EQ(buffer[i], 0); + } +} + +// While this test doesn't actually test anything, it can be used to check +// the compiler output to make sure the call to "ExplicitZeroMemory" is not +// optimized away. +TEST(ZeroMemoryTest, TestZeroMemoryUnused) { + static const size_t kBufferSize = 32; + uint8_t buffer[kBufferSize]; + ExplicitZeroMemory(buffer, sizeof(buffer)); +} + +} // namespace rtc