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 <stddef.h> 7 #include <stdio.h> 8 #include <stdlib.h> 9 #include <string.h> 10 #include <sys/stat.h> 11 #include <sys/types.h> 12 13 #include <algorithm> 14 #include <limits> 15 #include <memory> 16 17 #include "base/files/file_util.h" 18 #include "base/logging.h" 19 #include "base/memory/free_deleter.h" 20 #include "build/build_config.h" 21 #include "testing/gtest/include/gtest/gtest.h" 22 23 #if defined(OS_POSIX) 24 #include <sys/mman.h> 25 #include <unistd.h> 26 #endif 27 28 using std::nothrow; 29 using std::numeric_limits; 30 31 namespace { 32 33 // This function acts as a compiler optimization barrier. We use it to 34 // prevent the compiler from making an expression a compile-time constant. 35 // We also use it so that the compiler doesn't discard certain return values 36 // as something we don't need (see the comment with calloc below). 37 template <typename Type> 38 NOINLINE Type HideValueFromCompiler(volatile Type value) { 39 #if defined(__GNUC__) 40 // In a GCC compatible compiler (GCC or Clang), make this compiler barrier 41 // more robust than merely using "volatile". 42 __asm__ volatile ("" : "+r" (value)); 43 #endif // __GNUC__ 44 return value; 45 } 46 47 // Tcmalloc and Windows allocator shim support setting malloc limits. 48 // - NO_TCMALLOC (should be defined if compiled with use_allocator!="tcmalloc") 49 // - ADDRESS_SANITIZER and SYZYASAN because they have their own memory allocator 50 // - IOS does not use tcmalloc 51 // - OS_MACOSX does not use tcmalloc 52 // - Windows allocator shim defines ALLOCATOR_SHIM 53 #if (!defined(NO_TCMALLOC) || defined(ALLOCATOR_SHIM)) && \ 54 !defined(ADDRESS_SANITIZER) && !defined(OS_IOS) && !defined(OS_MACOSX) && \ 55 !defined(SYZYASAN) 56 #define MALLOC_OVERFLOW_TEST(function) function 57 #else 58 #define MALLOC_OVERFLOW_TEST(function) DISABLED_##function 59 #endif 60 61 #if defined(OS_LINUX) && defined(__x86_64__) 62 // Detect runtime TCMalloc bypasses. 63 bool IsTcMallocBypassed() { 64 // This should detect a TCMalloc bypass from Valgrind. 65 char* g_slice = getenv("G_SLICE"); 66 if (g_slice && !strcmp(g_slice, "always-malloc")) 67 return true; 68 return false; 69 } 70 #endif 71 72 // There are platforms where these tests are known to fail. We would like to 73 // be able to easily check the status on the bots, but marking tests as 74 // FAILS_ is too clunky. 75 void OverflowTestsSoftExpectTrue(bool overflow_detected) { 76 if (!overflow_detected) { 77 #if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_MACOSX) 78 // Sadly, on Linux, Android, and OSX we don't have a good story yet. Don't 79 // fail the test, but report. 80 printf("Platform has overflow: %s\n", 81 !overflow_detected ? "yes." : "no."); 82 #else 83 // Otherwise, fail the test. (Note: EXPECT are ok in subfunctions, ASSERT 84 // aren't). 85 EXPECT_TRUE(overflow_detected); 86 #endif 87 } 88 } 89 90 #if defined(OS_IOS) || defined(OS_WIN) || defined(OS_LINUX) 91 #define MAYBE_NewOverflow DISABLED_NewOverflow 92 #else 93 #define MAYBE_NewOverflow NewOverflow 94 #endif 95 // Test array[TooBig][X] and array[X][TooBig] allocations for int overflows. 96 // IOS doesn't honor nothrow, so disable the test there. 97 // Crashes on Windows Dbg builds, disable there as well. 98 // Disabled on Linux because failing Linux Valgrind bot, and Valgrind exclusions 99 // are not currently read. See http://crbug.com/582398 100 TEST(SecurityTest, MAYBE_NewOverflow) { 101 const size_t kArraySize = 4096; 102 // We want something "dynamic" here, so that the compiler doesn't 103 // immediately reject crazy arrays. 104 const size_t kDynamicArraySize = HideValueFromCompiler(kArraySize); 105 // numeric_limits are still not constexpr until we switch to C++11, so we 106 // use an ugly cast. 107 const size_t kMaxSizeT = ~static_cast<size_t>(0); 108 ASSERT_EQ(numeric_limits<size_t>::max(), kMaxSizeT); 109 const size_t kArraySize2 = kMaxSizeT / kArraySize + 10; 110 const size_t kDynamicArraySize2 = HideValueFromCompiler(kArraySize2); 111 { 112 std::unique_ptr<char[][kArraySize]> array_pointer( 113 new (nothrow) char[kDynamicArraySize2][kArraySize]); 114 OverflowTestsSoftExpectTrue(!array_pointer); 115 } 116 // On windows, the compiler prevents static array sizes of more than 117 // 0x7fffffff (error C2148). 118 #if defined(OS_WIN) && defined(ARCH_CPU_64_BITS) 119 ALLOW_UNUSED_LOCAL(kDynamicArraySize); 120 #else 121 { 122 std::unique_ptr<char[][kArraySize2]> array_pointer( 123 new (nothrow) char[kDynamicArraySize][kArraySize2]); 124 OverflowTestsSoftExpectTrue(!array_pointer); 125 } 126 #endif // !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS) 127 } 128 129 #if defined(OS_LINUX) && defined(__x86_64__) 130 // Check if ptr1 and ptr2 are separated by less than size chars. 131 bool ArePointersToSameArea(void* ptr1, void* ptr2, size_t size) { 132 ptrdiff_t ptr_diff = reinterpret_cast<char*>(std::max(ptr1, ptr2)) - 133 reinterpret_cast<char*>(std::min(ptr1, ptr2)); 134 return static_cast<size_t>(ptr_diff) <= size; 135 } 136 137 // Check if TCMalloc uses an underlying random memory allocator. 138 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(RandomMemoryAllocations)) { 139 if (IsTcMallocBypassed()) 140 return; 141 size_t kPageSize = 4096; // We support x86_64 only. 142 // Check that malloc() returns an address that is neither the kernel's 143 // un-hinted mmap area, nor the current brk() area. The first malloc() may 144 // not be at a random address because TCMalloc will first exhaust any memory 145 // that it has allocated early on, before starting the sophisticated 146 // allocators. 147 void* default_mmap_heap_address = 148 mmap(0, kPageSize, PROT_READ|PROT_WRITE, 149 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 150 ASSERT_NE(default_mmap_heap_address, 151 static_cast<void*>(MAP_FAILED)); 152 ASSERT_EQ(munmap(default_mmap_heap_address, kPageSize), 0); 153 void* brk_heap_address = sbrk(0); 154 ASSERT_NE(brk_heap_address, reinterpret_cast<void*>(-1)); 155 ASSERT_TRUE(brk_heap_address != NULL); 156 // 1 MB should get us past what TCMalloc pre-allocated before initializing 157 // the sophisticated allocators. 158 size_t kAllocSize = 1<<20; 159 std::unique_ptr<char, base::FreeDeleter> ptr( 160 static_cast<char*>(malloc(kAllocSize))); 161 ASSERT_TRUE(ptr != NULL); 162 // If two pointers are separated by less than 512MB, they are considered 163 // to be in the same area. 164 // Our random pointer could be anywhere within 0x3fffffffffff (46bits), 165 // and we are checking that it's not withing 1GB (30 bits) from two 166 // addresses (brk and mmap heap). We have roughly one chance out of 167 // 2^15 to flake. 168 const size_t kAreaRadius = 1<<29; 169 bool in_default_mmap_heap = ArePointersToSameArea( 170 ptr.get(), default_mmap_heap_address, kAreaRadius); 171 EXPECT_FALSE(in_default_mmap_heap); 172 173 bool in_default_brk_heap = ArePointersToSameArea( 174 ptr.get(), brk_heap_address, kAreaRadius); 175 EXPECT_FALSE(in_default_brk_heap); 176 177 // In the implementation, we always mask our random addresses with 178 // kRandomMask, so we use it as an additional detection mechanism. 179 const uintptr_t kRandomMask = 0x3fffffffffffULL; 180 bool impossible_random_address = 181 reinterpret_cast<uintptr_t>(ptr.get()) & ~kRandomMask; 182 EXPECT_FALSE(impossible_random_address); 183 } 184 185 #endif // defined(OS_LINUX) && defined(__x86_64__) 186 187 } // namespace 188
