1 // Copyright (c) 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include <fcntl.h> 6 #include <stdio.h> 7 #include <stdlib.h> 8 #include <string.h> 9 #include <sys/stat.h> 10 #include <sys/types.h> 11 12 #include <algorithm> 13 #include <limits> 14 15 #include "base/files/file_util.h" 16 #include "base/logging.h" 17 #include "base/memory/scoped_ptr.h" 18 #include "build/build_config.h" 19 #include "testing/gtest/include/gtest/gtest.h" 20 21 #if defined(OS_POSIX) 22 #include <sys/mman.h> 23 #include <unistd.h> 24 #endif 25 26 using std::nothrow; 27 using std::numeric_limits; 28 29 namespace { 30 31 // This function acts as a compiler optimization barrier. We use it to 32 // prevent the compiler from making an expression a compile-time constant. 33 // We also use it so that the compiler doesn't discard certain return values 34 // as something we don't need (see the comment with calloc below). 35 template <typename Type> 36 Type HideValueFromCompiler(volatile Type value) { 37 #if defined(__GNUC__) 38 // In a GCC compatible compiler (GCC or Clang), make this compiler barrier 39 // more robust than merely using "volatile". 40 __asm__ volatile ("" : "+r" (value)); 41 #endif // __GNUC__ 42 return value; 43 } 44 45 // - NO_TCMALLOC (should be defined if compiled with use_allocator!="tcmalloc") 46 // - ADDRESS_SANITIZER and SYZYASAN because they have their own memory allocator 47 // - IOS does not use tcmalloc 48 // - OS_MACOSX does not use tcmalloc 49 #if !defined(NO_TCMALLOC) && !defined(ADDRESS_SANITIZER) && \ 50 !defined(OS_IOS) && !defined(OS_MACOSX) && !defined(SYZYASAN) 51 #define TCMALLOC_TEST(function) function 52 #else 53 #define TCMALLOC_TEST(function) DISABLED_##function 54 #endif 55 56 // TODO(jln): switch to std::numeric_limits<int>::max() when we switch to 57 // C++11. 58 const size_t kTooBigAllocSize = INT_MAX; 59 60 // Detect runtime TCMalloc bypasses. 61 bool IsTcMallocBypassed() { 62 #if defined(OS_LINUX) 63 // This should detect a TCMalloc bypass from Valgrind. 64 char* g_slice = getenv("G_SLICE"); 65 if (g_slice && !strcmp(g_slice, "always-malloc")) 66 return true; 67 #elif defined(OS_WIN) 68 // This should detect a TCMalloc bypass from setting 69 // the CHROME_ALLOCATOR environment variable. 70 char* allocator = getenv("CHROME_ALLOCATOR"); 71 if (allocator && strcmp(allocator, "tcmalloc")) 72 return true; 73 #endif 74 return false; 75 } 76 77 bool CallocDiesOnOOM() { 78 // The sanitizers' calloc dies on OOM instead of returning NULL. 79 // The wrapper function in base/process_util_linux.cc that is used when we 80 // compile without TCMalloc will just die on OOM instead of returning NULL. 81 #if defined(ADDRESS_SANITIZER) || \ 82 defined(MEMORY_SANITIZER) || \ 83 defined(THREAD_SANITIZER) || \ 84 (defined(OS_LINUX) && defined(NO_TCMALLOC)) 85 return true; 86 #else 87 return false; 88 #endif 89 } 90 91 // Fake test that allow to know the state of TCMalloc by looking at bots. 92 TEST(SecurityTest, TCMALLOC_TEST(IsTCMallocDynamicallyBypassed)) { 93 printf("Malloc is dynamically bypassed: %s\n", 94 IsTcMallocBypassed() ? "yes." : "no."); 95 } 96 97 // The MemoryAllocationRestrictions* tests test that we can not allocate a 98 // memory range that cannot be indexed via an int. This is used to mitigate 99 // vulnerabilities in libraries that use int instead of size_t. See 100 // crbug.com/169327. 101 102 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsMalloc)) { 103 if (!IsTcMallocBypassed()) { 104 scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>( 105 HideValueFromCompiler(malloc(kTooBigAllocSize)))); 106 ASSERT_TRUE(!ptr); 107 } 108 } 109 110 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsCalloc)) { 111 if (!IsTcMallocBypassed()) { 112 scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>( 113 HideValueFromCompiler(calloc(kTooBigAllocSize, 1)))); 114 ASSERT_TRUE(!ptr); 115 } 116 } 117 118 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsRealloc)) { 119 if (!IsTcMallocBypassed()) { 120 char* orig_ptr = static_cast<char*>(malloc(1)); 121 ASSERT_TRUE(orig_ptr); 122 scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>( 123 HideValueFromCompiler(realloc(orig_ptr, kTooBigAllocSize)))); 124 ASSERT_TRUE(!ptr); 125 // If realloc() did not succeed, we need to free orig_ptr. 126 free(orig_ptr); 127 } 128 } 129 130 typedef struct { 131 char large_array[kTooBigAllocSize]; 132 } VeryLargeStruct; 133 134 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsNew)) { 135 if (!IsTcMallocBypassed()) { 136 scoped_ptr<VeryLargeStruct> ptr( 137 HideValueFromCompiler(new (nothrow) VeryLargeStruct)); 138 ASSERT_TRUE(!ptr); 139 } 140 } 141 142 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsNewArray)) { 143 if (!IsTcMallocBypassed()) { 144 scoped_ptr<char[]> ptr( 145 HideValueFromCompiler(new (nothrow) char[kTooBigAllocSize])); 146 ASSERT_TRUE(!ptr); 147 } 148 } 149 150 // The tests bellow check for overflows in new[] and calloc(). 151 152 #if defined(OS_IOS) || defined(OS_WIN) || defined(THREAD_SANITIZER) 153 #define DISABLE_ON_IOS_AND_WIN_AND_TSAN(function) DISABLED_##function 154 #else 155 #define DISABLE_ON_IOS_AND_WIN_AND_TSAN(function) function 156 #endif 157 158 // There are platforms where these tests are known to fail. We would like to 159 // be able to easily check the status on the bots, but marking tests as 160 // FAILS_ is too clunky. 161 void OverflowTestsSoftExpectTrue(bool overflow_detected) { 162 if (!overflow_detected) { 163 #if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_MACOSX) 164 // Sadly, on Linux, Android, and OSX we don't have a good story yet. Don't 165 // fail the test, but report. 166 printf("Platform has overflow: %s\n", 167 !overflow_detected ? "yes." : "no."); 168 #else 169 // Otherwise, fail the test. (Note: EXPECT are ok in subfunctions, ASSERT 170 // aren't). 171 EXPECT_TRUE(overflow_detected); 172 #endif 173 } 174 } 175 176 // Test array[TooBig][X] and array[X][TooBig] allocations for int overflows. 177 // IOS doesn't honor nothrow, so disable the test there. 178 // Crashes on Windows Dbg builds, disable there as well. 179 TEST(SecurityTest, DISABLE_ON_IOS_AND_WIN_AND_TSAN(NewOverflow)) { 180 const size_t kArraySize = 4096; 181 // We want something "dynamic" here, so that the compiler doesn't 182 // immediately reject crazy arrays. 183 const size_t kDynamicArraySize = HideValueFromCompiler(kArraySize); 184 // numeric_limits are still not constexpr until we switch to C++11, so we 185 // use an ugly cast. 186 const size_t kMaxSizeT = ~static_cast<size_t>(0); 187 ASSERT_EQ(numeric_limits<size_t>::max(), kMaxSizeT); 188 const size_t kArraySize2 = kMaxSizeT / kArraySize + 10; 189 const size_t kDynamicArraySize2 = HideValueFromCompiler(kArraySize2); 190 { 191 scoped_ptr<char[][kArraySize]> array_pointer(new (nothrow) 192 char[kDynamicArraySize2][kArraySize]); 193 OverflowTestsSoftExpectTrue(!array_pointer); 194 } 195 // On windows, the compiler prevents static array sizes of more than 196 // 0x7fffffff (error C2148). 197 #if !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS) 198 { 199 scoped_ptr<char[][kArraySize2]> array_pointer(new (nothrow) 200 char[kDynamicArraySize][kArraySize2]); 201 OverflowTestsSoftExpectTrue(!array_pointer); 202 } 203 #endif // !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS) 204 } 205 206 // Call calloc(), eventually free the memory and return whether or not 207 // calloc() did succeed. 208 bool CallocReturnsNull(size_t nmemb, size_t size) { 209 scoped_ptr<char, base::FreeDeleter> array_pointer( 210 static_cast<char*>(calloc(nmemb, size))); 211 // We need the call to HideValueFromCompiler(): we have seen LLVM 212 // optimize away the call to calloc() entirely and assume 213 // the pointer to not be NULL. 214 return HideValueFromCompiler(array_pointer.get()) == NULL; 215 } 216 217 // Test if calloc() can overflow. 218 TEST(SecurityTest, CallocOverflow) { 219 const size_t kArraySize = 4096; 220 const size_t kMaxSizeT = numeric_limits<size_t>::max(); 221 const size_t kArraySize2 = kMaxSizeT / kArraySize + 10; 222 if (!CallocDiesOnOOM()) { 223 EXPECT_TRUE(CallocReturnsNull(kArraySize, kArraySize2)); 224 EXPECT_TRUE(CallocReturnsNull(kArraySize2, kArraySize)); 225 } else { 226 // It's also ok for calloc to just terminate the process. 227 #if defined(GTEST_HAS_DEATH_TEST) 228 EXPECT_DEATH(CallocReturnsNull(kArraySize, kArraySize2), ""); 229 EXPECT_DEATH(CallocReturnsNull(kArraySize2, kArraySize), ""); 230 #endif // GTEST_HAS_DEATH_TEST 231 } 232 } 233 234 #if defined(OS_LINUX) && defined(__x86_64__) 235 // Check if ptr1 and ptr2 are separated by less than size chars. 236 bool ArePointersToSameArea(void* ptr1, void* ptr2, size_t size) { 237 ptrdiff_t ptr_diff = reinterpret_cast<char*>(std::max(ptr1, ptr2)) - 238 reinterpret_cast<char*>(std::min(ptr1, ptr2)); 239 return static_cast<size_t>(ptr_diff) <= size; 240 } 241 242 // Check if TCMalloc uses an underlying random memory allocator. 243 TEST(SecurityTest, TCMALLOC_TEST(RandomMemoryAllocations)) { 244 if (IsTcMallocBypassed()) 245 return; 246 size_t kPageSize = 4096; // We support x86_64 only. 247 // Check that malloc() returns an address that is neither the kernel's 248 // un-hinted mmap area, nor the current brk() area. The first malloc() may 249 // not be at a random address because TCMalloc will first exhaust any memory 250 // that it has allocated early on, before starting the sophisticated 251 // allocators. 252 void* default_mmap_heap_address = 253 mmap(0, kPageSize, PROT_READ|PROT_WRITE, 254 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 255 ASSERT_NE(default_mmap_heap_address, 256 static_cast<void*>(MAP_FAILED)); 257 ASSERT_EQ(munmap(default_mmap_heap_address, kPageSize), 0); 258 void* brk_heap_address = sbrk(0); 259 ASSERT_NE(brk_heap_address, reinterpret_cast<void*>(-1)); 260 ASSERT_TRUE(brk_heap_address != NULL); 261 // 1 MB should get us past what TCMalloc pre-allocated before initializing 262 // the sophisticated allocators. 263 size_t kAllocSize = 1<<20; 264 scoped_ptr<char, base::FreeDeleter> ptr( 265 static_cast<char*>(malloc(kAllocSize))); 266 ASSERT_TRUE(ptr != NULL); 267 // If two pointers are separated by less than 512MB, they are considered 268 // to be in the same area. 269 // Our random pointer could be anywhere within 0x3fffffffffff (46bits), 270 // and we are checking that it's not withing 1GB (30 bits) from two 271 // addresses (brk and mmap heap). We have roughly one chance out of 272 // 2^15 to flake. 273 const size_t kAreaRadius = 1<<29; 274 bool in_default_mmap_heap = ArePointersToSameArea( 275 ptr.get(), default_mmap_heap_address, kAreaRadius); 276 EXPECT_FALSE(in_default_mmap_heap); 277 278 bool in_default_brk_heap = ArePointersToSameArea( 279 ptr.get(), brk_heap_address, kAreaRadius); 280 EXPECT_FALSE(in_default_brk_heap); 281 282 // In the implementation, we always mask our random addresses with 283 // kRandomMask, so we use it as an additional detection mechanism. 284 const uintptr_t kRandomMask = 0x3fffffffffffULL; 285 bool impossible_random_address = 286 reinterpret_cast<uintptr_t>(ptr.get()) & ~kRandomMask; 287 EXPECT_FALSE(impossible_random_address); 288 } 289 290 #endif // defined(OS_LINUX) && defined(__x86_64__) 291 292 } // namespace 293
