1 // Copyright 2024 The Abseil Authors
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/base/internal/poison.h"
16
17 #include <cstdlib>
18
19 #include "absl/base/config.h"
20 #include "absl/base/internal/direct_mmap.h"
21
22 #ifndef _WIN32
23 #include <unistd.h>
24 #endif
25
26 #if defined(ABSL_HAVE_ADDRESS_SANITIZER)
27 #include <sanitizer/asan_interface.h>
28 #elif defined(ABSL_HAVE_MEMORY_SANITIZER)
29 #include <sanitizer/msan_interface.h>
30 #elif defined(ABSL_HAVE_MMAP)
31 #include <sys/mman.h>
32 #endif
33
34 #if defined(_WIN32)
35 #include <windows.h>
36 #endif
37
38 namespace absl {
39 ABSL_NAMESPACE_BEGIN
40 namespace base_internal {
41
42 namespace {
43
GetPageSize()44 size_t GetPageSize() {
45 #ifdef _WIN32
46 SYSTEM_INFO system_info;
47 GetSystemInfo(&system_info);
48 return system_info.dwPageSize;
49 #elif defined(__wasm__) || defined(__asmjs__) || defined(__hexagon__)
50 return getpagesize();
51 #else
52 return static_cast<size_t>(sysconf(_SC_PAGESIZE));
53 #endif
54 }
55
56 } // namespace
57
InitializePoisonedPointerInternal()58 void* InitializePoisonedPointerInternal() {
59 const size_t block_size = GetPageSize();
60 #if defined(ABSL_HAVE_ADDRESS_SANITIZER)
61 void* data = malloc(block_size);
62 ASAN_POISON_MEMORY_REGION(data, block_size);
63 #elif defined(ABSL_HAVE_MEMORY_SANITIZER)
64 void* data = malloc(block_size);
65 __msan_poison(data, block_size);
66 #elif defined(ABSL_HAVE_MMAP)
67 void* data = DirectMmap(nullptr, block_size, PROT_NONE,
68 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
69 if (data == MAP_FAILED) return GetBadPointerInternal();
70 #elif defined(_WIN32)
71 void* data = VirtualAlloc(nullptr, block_size, MEM_RESERVE | MEM_COMMIT,
72 PAGE_NOACCESS);
73 if (data == nullptr) return GetBadPointerInternal();
74 #else
75 return GetBadPointerInternal();
76 #endif
77 // Return the middle of the block so that dereferences before and after the
78 // pointer will both crash.
79 return static_cast<char*>(data) + block_size / 2;
80 }
81
82 } // namespace base_internal
83 ABSL_NAMESPACE_END
84 } // namespace absl
85