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
16 #include "base/files/file_util.h"
17 #include "base/logging.h"
18 #include "base/memory/scoped_ptr.h"
19 #include "build/build_config.h"
20 #include "testing/gtest/include/gtest/gtest.h"
21
22 #if defined(OS_POSIX)
23 #include <sys/mman.h>
24 #include <unistd.h>
25 #endif
26
27 using std::nothrow;
28 using std::numeric_limits;
29
30 namespace {
31
32 // This function acts as a compiler optimization barrier. We use it to
33 // prevent the compiler from making an expression a compile-time constant.
34 // We also use it so that the compiler doesn't discard certain return values
35 // as something we don't need (see the comment with calloc below).
36 template <typename Type>
HideValueFromCompiler(volatile Type value)37 NOINLINE Type HideValueFromCompiler(volatile Type value) {
38 #if defined(__GNUC__)
39 // In a GCC compatible compiler (GCC or Clang), make this compiler barrier
40 // more robust than merely using "volatile".
41 __asm__ volatile ("" : "+r" (value));
42 #endif // __GNUC__
43 return value;
44 }
45
46 // Tcmalloc and Windows allocator shim support setting malloc limits.
47 // - NO_TCMALLOC (should be defined if compiled with use_allocator!="tcmalloc")
48 // - ADDRESS_SANITIZER and SYZYASAN because they have their own memory allocator
49 // - IOS does not use tcmalloc
50 // - OS_MACOSX does not use tcmalloc
51 // - Windows allocator shim defines ALLOCATOR_SHIM
52 #if (!defined(NO_TCMALLOC) || defined(ALLOCATOR_SHIM)) && \
53 !defined(ADDRESS_SANITIZER) && !defined(OS_IOS) && !defined(OS_MACOSX) && \
54 !defined(SYZYASAN)
55 #define MALLOC_OVERFLOW_TEST(function) function
56 #else
57 #define MALLOC_OVERFLOW_TEST(function) DISABLED_##function
58 #endif
59
60 #if defined(OS_LINUX) && defined(__x86_64__)
61 // Detect runtime TCMalloc bypasses.
IsTcMallocBypassed()62 bool IsTcMallocBypassed() {
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 return false;
68 }
69 #endif
70
71 // There are platforms where these tests are known to fail. We would like to
72 // be able to easily check the status on the bots, but marking tests as
73 // FAILS_ is too clunky.
OverflowTestsSoftExpectTrue(bool overflow_detected)74 void OverflowTestsSoftExpectTrue(bool overflow_detected) {
75 if (!overflow_detected) {
76 #if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_MACOSX)
77 // Sadly, on Linux, Android, and OSX we don't have a good story yet. Don't
78 // fail the test, but report.
79 printf("Platform has overflow: %s\n",
80 !overflow_detected ? "yes." : "no.");
81 #else
82 // Otherwise, fail the test. (Note: EXPECT are ok in subfunctions, ASSERT
83 // aren't).
84 EXPECT_TRUE(overflow_detected);
85 #endif
86 }
87 }
88
89 #if defined(OS_IOS) || defined(OS_WIN) || defined(OS_MACOSX)
90 #define MAYBE_NewOverflow DISABLED_NewOverflow
91 #else
92 #define MAYBE_NewOverflow NewOverflow
93 #endif
94 // Test array[TooBig][X] and array[X][TooBig] allocations for int overflows.
95 // IOS doesn't honor nothrow, so disable the test there.
96 // Crashes on Windows Dbg builds, disable there as well.
97 // Fails on Mac 10.8 http://crbug.com/227092
TEST(SecurityTest,MAYBE_NewOverflow)98 TEST(SecurityTest, MAYBE_NewOverflow) {
99 const size_t kArraySize = 4096;
100 // We want something "dynamic" here, so that the compiler doesn't
101 // immediately reject crazy arrays.
102 const size_t kDynamicArraySize = HideValueFromCompiler(kArraySize);
103 // numeric_limits are still not constexpr until we switch to C++11, so we
104 // use an ugly cast.
105 const size_t kMaxSizeT = ~static_cast<size_t>(0);
106 ASSERT_EQ(numeric_limits<size_t>::max(), kMaxSizeT);
107 const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
108 const size_t kDynamicArraySize2 = HideValueFromCompiler(kArraySize2);
109 {
110 scoped_ptr<char[][kArraySize]> array_pointer(new (nothrow)
111 char[kDynamicArraySize2][kArraySize]);
112 OverflowTestsSoftExpectTrue(!array_pointer);
113 }
114 // On windows, the compiler prevents static array sizes of more than
115 // 0x7fffffff (error C2148).
116 #if defined(OS_WIN) && defined(ARCH_CPU_64_BITS)
117 ALLOW_UNUSED_LOCAL(kDynamicArraySize);
118 #else
119 {
120 scoped_ptr<char[][kArraySize2]> array_pointer(new (nothrow)
121 char[kDynamicArraySize][kArraySize2]);
122 OverflowTestsSoftExpectTrue(!array_pointer);
123 }
124 #endif // !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS)
125 }
126
127 #if defined(OS_LINUX) && defined(__x86_64__)
128 // Check if ptr1 and ptr2 are separated by less than size chars.
ArePointersToSameArea(void * ptr1,void * ptr2,size_t size)129 bool ArePointersToSameArea(void* ptr1, void* ptr2, size_t size) {
130 ptrdiff_t ptr_diff = reinterpret_cast<char*>(std::max(ptr1, ptr2)) -
131 reinterpret_cast<char*>(std::min(ptr1, ptr2));
132 return static_cast<size_t>(ptr_diff) <= size;
133 }
134
135 // Check if TCMalloc uses an underlying random memory allocator.
TEST(SecurityTest,MALLOC_OVERFLOW_TEST (RandomMemoryAllocations))136 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(RandomMemoryAllocations)) {
137 if (IsTcMallocBypassed())
138 return;
139 size_t kPageSize = 4096; // We support x86_64 only.
140 // Check that malloc() returns an address that is neither the kernel's
141 // un-hinted mmap area, nor the current brk() area. The first malloc() may
142 // not be at a random address because TCMalloc will first exhaust any memory
143 // that it has allocated early on, before starting the sophisticated
144 // allocators.
145 void* default_mmap_heap_address =
146 mmap(0, kPageSize, PROT_READ|PROT_WRITE,
147 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
148 ASSERT_NE(default_mmap_heap_address,
149 static_cast<void*>(MAP_FAILED));
150 ASSERT_EQ(munmap(default_mmap_heap_address, kPageSize), 0);
151 void* brk_heap_address = sbrk(0);
152 ASSERT_NE(brk_heap_address, reinterpret_cast<void*>(-1));
153 ASSERT_TRUE(brk_heap_address != NULL);
154 // 1 MB should get us past what TCMalloc pre-allocated before initializing
155 // the sophisticated allocators.
156 size_t kAllocSize = 1<<20;
157 scoped_ptr<char, base::FreeDeleter> ptr(
158 static_cast<char*>(malloc(kAllocSize)));
159 ASSERT_TRUE(ptr != NULL);
160 // If two pointers are separated by less than 512MB, they are considered
161 // to be in the same area.
162 // Our random pointer could be anywhere within 0x3fffffffffff (46bits),
163 // and we are checking that it's not withing 1GB (30 bits) from two
164 // addresses (brk and mmap heap). We have roughly one chance out of
165 // 2^15 to flake.
166 const size_t kAreaRadius = 1<<29;
167 bool in_default_mmap_heap = ArePointersToSameArea(
168 ptr.get(), default_mmap_heap_address, kAreaRadius);
169 EXPECT_FALSE(in_default_mmap_heap);
170
171 bool in_default_brk_heap = ArePointersToSameArea(
172 ptr.get(), brk_heap_address, kAreaRadius);
173 EXPECT_FALSE(in_default_brk_heap);
174
175 // In the implementation, we always mask our random addresses with
176 // kRandomMask, so we use it as an additional detection mechanism.
177 const uintptr_t kRandomMask = 0x3fffffffffffULL;
178 bool impossible_random_address =
179 reinterpret_cast<uintptr_t>(ptr.get()) & ~kRandomMask;
180 EXPECT_FALSE(impossible_random_address);
181 }
182
183 #endif // defined(OS_LINUX) && defined(__x86_64__)
184
185 } // namespace
186