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>
HideValueFromCompiler(volatile Type value)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.
IsTcMallocBypassed()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.
OverflowTestsSoftExpectTrue(bool overflow_detected)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
TEST(SecurityTest,MAYBE_NewOverflow)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.
ArePointersToSameArea(void * ptr1,void * ptr2,size_t size)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.
TEST(SecurityTest,MALLOC_OVERFLOW_TEST (RandomMemoryAllocations))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