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
26using std::nothrow;
27using std::numeric_limits;
28
29namespace {
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).
35template <typename Type>
36Type 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.
58const size_t kTooBigAllocSize = INT_MAX;
59
60// Detect runtime TCMalloc bypasses.
61bool 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
77bool 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.
92TEST(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
102TEST(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
110TEST(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
118TEST(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
130typedef struct {
131  char large_array[kTooBigAllocSize];
132} VeryLargeStruct;
133
134TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsNew)) {
135  if (!IsTcMallocBypassed()) {
136    scoped_ptr<VeryLargeStruct> ptr(
137        HideValueFromCompiler(new (nothrow) VeryLargeStruct));
138    ASSERT_TRUE(!ptr);
139  }
140}
141
142TEST(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.
161void 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.
179TEST(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.
208bool 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.
218TEST(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.
236bool 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.
243TEST(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