3 files changed, 182 insertions, 0 deletions
diff --git a/absl/base/internal/poison.cc b/absl/base/internal/poison.cc
new file mode 100644
index 00000000..9afa0687
--- /dev/null
+++ b/absl/base/internal/poison.cc
@@ -0,0 +1,82 @@
+// Copyright 2024 The Abseil Authors
+//
+// 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
+//
+//     https://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 "absl/base/internal/poison.h"
+
+#include <cstdlib>
+
+#include "absl/base/config.h"
+#include "absl/base/internal/direct_mmap.h"
+
+#ifndef _WIN32
+#include <unistd.h>
+#endif
+
+#if defined(ABSL_HAVE_ADDRESS_SANITIZER)
+#include <sanitizer/asan_interface.h>
+#elif defined(ABSL_HAVE_MEMORY_SANITIZER)
+#include <sanitizer/msan_interface.h>
+#elif defined(ABSL_HAVE_MMAP)
+#include <sys/mman.h>
+#elif defined(_WIN32)
+#include <windows.h>
+#endif
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace base_internal {
+
+namespace {
+
+size_t GetPageSize() {
+#ifdef _WIN32
+  SYSTEM_INFO system_info;
+  GetSystemInfo(&system_info);
+  return system_info.dwPageSize;
+#elif defined(__wasm__) || defined(__asmjs__) || defined(__hexagon__)
+  return getpagesize();
+#else
+  return static_cast<size_t>(sysconf(_SC_PAGESIZE));
+#endif
+}
+
+}  // namespace
+
+void* InitializePoisonedPointerInternal() {
+  const size_t block_size = GetPageSize();
+#if defined(ABSL_HAVE_ADDRESS_SANITIZER)
+  void* data = malloc(block_size);
+  ASAN_POISON_MEMORY_REGION(data, block_size);
+#elif defined(ABSL_HAVE_MEMORY_SANITIZER)
+  void* data = malloc(block_size);
+  __msan_poison(data, block_size);
+#elif defined(ABSL_HAVE_MMAP)
+  void* data = DirectMmap(nullptr, block_size, PROT_NONE,
+                          MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (data == MAP_FAILED) return GetBadPointerInternal();
+#elif defined(_WIN32)
+  void* data = VirtualAlloc(nullptr, block_size, MEM_RESERVE | MEM_COMMIT,
+                            PAGE_NOACCESS);
+  if (data == nullptr) return GetBadPointerInternal();
+#else
+  return GetBadPointerInternal();
+#endif
+  // Return the middle of the block so that dereferences before and after the
+  // pointer will both crash.
+  return static_cast<char*>(data) + block_size / 2;
+}
+
+}  // namespace base_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
diff --git a/absl/base/internal/poison.h b/absl/base/internal/poison.h
new file mode 100644
index 00000000..28113bdd
--- /dev/null
+++ b/absl/base/internal/poison.h
@@ -0,0 +1,59 @@
+// Copyright 2024 The Abseil Authors
+//
+// 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
+//
+//     https://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.
+
+#ifndef ABSL_BASE_INTERNAL_POISON_H_
+#define ABSL_BASE_INTERNAL_POISON_H_
+
+#include <cstdint>
+
+#include "absl/base/config.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace base_internal {
+
+inline void* GetBadPointerInternal() {
+  // A likely bad pointer. Pointers are required to have high bits that are all
+  // zero or all one for certain 64-bit CPUs. This pointer value will hopefully
+  // cause a crash on dereference and also be clearly recognizable as invalid.
+  constexpr uint64_t kBadPtr = 0xBAD0BAD0BAD0BAD0;
+  auto ret = reinterpret_cast<void*>(static_cast<uintptr_t>(kBadPtr));
+#ifndef _MSC_VER  // MSVC doesn't support inline asm with `volatile`.
+  // Try to prevent the compiler from optimizing out the undefined behavior.
+  asm volatile("" : : "r"(ret) :);  // NOLINT
+#endif
+  return ret;
+}
+
+void* InitializePoisonedPointerInternal();
+
+inline void* get_poisoned_pointer() {
+#if defined(NDEBUG) && !defined(ABSL_HAVE_ADDRESS_SANITIZER) && \
+    !defined(ABSL_HAVE_MEMORY_SANITIZER)
+  // In optimized non-sanitized builds, avoid the function-local static because
+  // of the codegen and runtime cost.
+  return GetBadPointerInternal();
+#else
+  // Non-optimized builds may use more robust implementation. Note that we can't
+  // use a static global because Chromium doesn't allow non-constinit globals.
+  static void* ptr = InitializePoisonedPointerInternal();
+  return ptr;
+#endif
+}
+
+}  // namespace base_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_BASE_INTERNAL_POISON_H_
diff --git a/absl/base/internal/poison_test.cc b/absl/base/internal/poison_test.cc
new file mode 100644
index 00000000..6596b454
--- /dev/null
+++ b/absl/base/internal/poison_test.cc
@@ -0,0 +1,41 @@
+// Copyright 2024 The Abseil Authors
+//
+// 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
+//
+//     https://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 "absl/base/internal/poison.h"
+
+#include <iostream>
+
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace base_internal {
+namespace {
+
+TEST(PoisonTest, CrashesOnDereference) {
+#ifdef __ANDROID__
+  GTEST_SKIP() << "On Android, poisoned pointer dereference times out instead "
+                  "of crashing.";
+#endif
+  int* poisoned_ptr = static_cast<int*>(get_poisoned_pointer());
+  EXPECT_DEATH_IF_SUPPORTED(std::cout << *poisoned_ptr, "");
+  EXPECT_DEATH_IF_SUPPORTED(std::cout << *(poisoned_ptr - 10), "");
+  EXPECT_DEATH_IF_SUPPORTED(std::cout << *(poisoned_ptr + 10), "");
+}
+
+}  // namespace
+}  // namespace base_internal
+ABSL_NAMESPACE_END
+}  // namespace absl