blob: 07ba6f5a0f2af7fed188fa441beffa601c8a2bb3 [file] [log] [blame]
// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <algorithm>
#include <limits>
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "build/build_config.h"
#include "testing/gtest/include/gtest/gtest.h"
#if defined(OS_POSIX)
#include <sys/mman.h>
#include <unistd.h>
#endif
#if defined(OS_WIN)
#include <new.h>
#endif
using std::nothrow;
using std::numeric_limits;
namespace {
#if defined(OS_WIN)
// This is a permitted size but exhausts memory pretty quickly.
const size_t kLargePermittedAllocation = 0x7FFFE000;
int OnNoMemory(size_t) {
_exit(1);
}
void ExhaustMemoryWithMalloc() {
for (;;) {
// Without the |volatile|, clang optimizes away the allocation.
void* volatile buf = malloc(kLargePermittedAllocation);
if (!buf)
break;
}
}
void ExhaustMemoryWithRealloc() {
size_t size = kLargePermittedAllocation;
void* buf = malloc(size);
if (!buf)
return;
for (;;) {
size += kLargePermittedAllocation;
void* new_buf = realloc(buf, size);
if (!buf)
break;
buf = new_buf;
}
}
#endif
// This function acts as a compiler optimization barrier. We use it to
// prevent the compiler from making an expression a compile-time constant.
// We also use it so that the compiler doesn't discard certain return values
// as something we don't need (see the comment with calloc below).
template <typename Type>
NOINLINE Type HideValueFromCompiler(volatile Type value) {
#if defined(__GNUC__)
// In a GCC compatible compiler (GCC or Clang), make this compiler barrier
// more robust than merely using "volatile".
__asm__ volatile ("" : "+r" (value));
#endif // __GNUC__
return value;
}
// Tcmalloc and Windows allocator shim support setting malloc limits.
// - NO_TCMALLOC (should be defined if compiled with use_allocator!="tcmalloc")
// - ADDRESS_SANITIZER and SYZYASAN because they have their own memory allocator
// - IOS does not use tcmalloc
// - OS_MACOSX does not use tcmalloc
// - Windows allocator shim defines ALLOCATOR_SHIM
#if (!defined(NO_TCMALLOC) || defined(ALLOCATOR_SHIM)) && \
!defined(ADDRESS_SANITIZER) && !defined(OS_IOS) && !defined(OS_MACOSX) && \
!defined(SYZYASAN)
#define MALLOC_OVERFLOW_TEST(function) function
#else
#define MALLOC_OVERFLOW_TEST(function) DISABLED_##function
#endif
// TODO(jln): switch to std::numeric_limits<int>::max() when we switch to
// C++11.
const size_t kTooBigAllocSize = INT_MAX;
// Detect runtime TCMalloc bypasses.
bool IsTcMallocBypassed() {
#if defined(OS_LINUX)
// This should detect a TCMalloc bypass from Valgrind.
char* g_slice = getenv("G_SLICE");
if (g_slice && !strcmp(g_slice, "always-malloc"))
return true;
#endif
return false;
}
bool CallocDiesOnOOM() {
// The sanitizers' calloc dies on OOM instead of returning NULL.
// The wrapper function in base/process_util_linux.cc that is used when we
// compile without TCMalloc will just die on OOM instead of returning NULL.
#if defined(ADDRESS_SANITIZER) || \
defined(MEMORY_SANITIZER) || \
defined(THREAD_SANITIZER) || \
(defined(OS_LINUX) && defined(NO_TCMALLOC))
return true;
#else
return false;
#endif
}
// Fake test that allow to know the state of TCMalloc by looking at bots.
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(IsTCMallocDynamicallyBypassed)) {
printf("Malloc is dynamically bypassed: %s\n",
IsTcMallocBypassed() ? "yes." : "no.");
}
// The MemoryAllocationRestrictions* tests test that we can not allocate a
// memory range that cannot be indexed via an int. This is used to mitigate
// vulnerabilities in libraries that use int instead of size_t. See
// crbug.com/169327.
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsMalloc)) {
if (!IsTcMallocBypassed()) {
scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
HideValueFromCompiler(malloc(kTooBigAllocSize))));
ASSERT_TRUE(!ptr);
}
}
#if defined(GTEST_HAS_DEATH_TEST) && defined(OS_WIN)
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationMallocDeathTest)) {
_set_new_handler(&OnNoMemory);
_set_new_mode(1);
{
scoped_ptr<char, base::FreeDeleter> ptr;
EXPECT_DEATH(ptr.reset(static_cast<char*>(
HideValueFromCompiler(malloc(kTooBigAllocSize)))),
"");
ASSERT_TRUE(!ptr);
}
_set_new_handler(NULL);
_set_new_mode(0);
}
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationExhaustDeathTest)) {
_set_new_handler(&OnNoMemory);
_set_new_mode(1);
{
ASSERT_DEATH(ExhaustMemoryWithMalloc(), "");
}
_set_new_handler(NULL);
_set_new_mode(0);
}
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryReallocationExhaustDeathTest)) {
_set_new_handler(&OnNoMemory);
_set_new_mode(1);
{
ASSERT_DEATH(ExhaustMemoryWithRealloc(), "");
}
_set_new_handler(NULL);
_set_new_mode(0);
}
#endif
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsCalloc)) {
if (!IsTcMallocBypassed()) {
scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
HideValueFromCompiler(calloc(kTooBigAllocSize, 1))));
ASSERT_TRUE(!ptr);
}
}
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsRealloc)) {
if (!IsTcMallocBypassed()) {
char* orig_ptr = static_cast<char*>(malloc(1));
ASSERT_TRUE(orig_ptr);
scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
HideValueFromCompiler(realloc(orig_ptr, kTooBigAllocSize))));
ASSERT_TRUE(!ptr);
// If realloc() did not succeed, we need to free orig_ptr.
free(orig_ptr);
}
}
typedef struct {
char large_array[kTooBigAllocSize];
} VeryLargeStruct;
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsNew)) {
if (!IsTcMallocBypassed()) {
scoped_ptr<VeryLargeStruct> ptr(
HideValueFromCompiler(new (nothrow) VeryLargeStruct));
ASSERT_TRUE(!ptr);
}
}
#if defined(GTEST_HAS_DEATH_TEST) && defined(OS_WIN)
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationNewDeathTest)) {
_set_new_handler(&OnNoMemory);
{
scoped_ptr<VeryLargeStruct> ptr;
EXPECT_DEATH(
ptr.reset(HideValueFromCompiler(new (nothrow) VeryLargeStruct)), "");
ASSERT_TRUE(!ptr);
}
_set_new_handler(NULL);
}
#endif
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsNewArray)) {
if (!IsTcMallocBypassed()) {
scoped_ptr<char[]> ptr(
HideValueFromCompiler(new (nothrow) char[kTooBigAllocSize]));
ASSERT_TRUE(!ptr);
}
}
// The tests bellow check for overflows in new[] and calloc().
// There are platforms where these tests are known to fail. We would like to
// be able to easily check the status on the bots, but marking tests as
// FAILS_ is too clunky.
void OverflowTestsSoftExpectTrue(bool overflow_detected) {
if (!overflow_detected) {
#if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_MACOSX)
// Sadly, on Linux, Android, and OSX we don't have a good story yet. Don't
// fail the test, but report.
printf("Platform has overflow: %s\n",
!overflow_detected ? "yes." : "no.");
#else
// Otherwise, fail the test. (Note: EXPECT are ok in subfunctions, ASSERT
// aren't).
EXPECT_TRUE(overflow_detected);
#endif
}
}
#if defined(OS_IOS) || defined(OS_WIN) || defined(THREAD_SANITIZER) || defined(OS_MACOSX)
#define MAYBE_NewOverflow DISABLED_NewOverflow
#else
#define MAYBE_NewOverflow NewOverflow
#endif
// Test array[TooBig][X] and array[X][TooBig] allocations for int overflows.
// IOS doesn't honor nothrow, so disable the test there.
// Crashes on Windows Dbg builds, disable there as well.
// Fails on Mac 10.8 http://crbug.com/227092
TEST(SecurityTest, MAYBE_NewOverflow) {
const size_t kArraySize = 4096;
// We want something "dynamic" here, so that the compiler doesn't
// immediately reject crazy arrays.
const size_t kDynamicArraySize = HideValueFromCompiler(kArraySize);
// numeric_limits are still not constexpr until we switch to C++11, so we
// use an ugly cast.
const size_t kMaxSizeT = ~static_cast<size_t>(0);
ASSERT_EQ(numeric_limits<size_t>::max(), kMaxSizeT);
const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
const size_t kDynamicArraySize2 = HideValueFromCompiler(kArraySize2);
{
scoped_ptr<char[][kArraySize]> array_pointer(new (nothrow)
char[kDynamicArraySize2][kArraySize]);
OverflowTestsSoftExpectTrue(!array_pointer);
}
// On windows, the compiler prevents static array sizes of more than
// 0x7fffffff (error C2148).
#if defined(OS_WIN) && defined(ARCH_CPU_64_BITS)
ALLOW_UNUSED_LOCAL(kDynamicArraySize);
#else
{
scoped_ptr<char[][kArraySize2]> array_pointer(new (nothrow)
char[kDynamicArraySize][kArraySize2]);
OverflowTestsSoftExpectTrue(!array_pointer);
}
#endif // !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS)
}
// Call calloc(), eventually free the memory and return whether or not
// calloc() did succeed.
bool CallocReturnsNull(size_t nmemb, size_t size) {
scoped_ptr<char, base::FreeDeleter> array_pointer(
static_cast<char*>(calloc(nmemb, size)));
// We need the call to HideValueFromCompiler(): we have seen LLVM
// optimize away the call to calloc() entirely and assume the pointer to not
// be NULL.
return HideValueFromCompiler(array_pointer.get()) == NULL;
}
// Test if calloc() can overflow.
TEST(SecurityTest, CallocOverflow) {
const size_t kArraySize = 4096;
const size_t kMaxSizeT = numeric_limits<size_t>::max();
const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
if (!CallocDiesOnOOM()) {
EXPECT_TRUE(CallocReturnsNull(kArraySize, kArraySize2));
EXPECT_TRUE(CallocReturnsNull(kArraySize2, kArraySize));
} else {
// It's also ok for calloc to just terminate the process.
#if defined(GTEST_HAS_DEATH_TEST)
EXPECT_DEATH(CallocReturnsNull(kArraySize, kArraySize2), "");
EXPECT_DEATH(CallocReturnsNull(kArraySize2, kArraySize), "");
#endif // GTEST_HAS_DEATH_TEST
}
}
#if defined(OS_LINUX) && defined(__x86_64__)
// Check if ptr1 and ptr2 are separated by less than size chars.
bool ArePointersToSameArea(void* ptr1, void* ptr2, size_t size) {
ptrdiff_t ptr_diff = reinterpret_cast<char*>(std::max(ptr1, ptr2)) -
reinterpret_cast<char*>(std::min(ptr1, ptr2));
return static_cast<size_t>(ptr_diff) <= size;
}
// Check if TCMalloc uses an underlying random memory allocator.
TEST(SecurityTest, MALLOC_OVERFLOW_TEST(RandomMemoryAllocations)) {
if (IsTcMallocBypassed())
return;
size_t kPageSize = 4096; // We support x86_64 only.
// Check that malloc() returns an address that is neither the kernel's
// un-hinted mmap area, nor the current brk() area. The first malloc() may
// not be at a random address because TCMalloc will first exhaust any memory
// that it has allocated early on, before starting the sophisticated
// allocators.
void* default_mmap_heap_address =
mmap(0, kPageSize, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
ASSERT_NE(default_mmap_heap_address,
static_cast<void*>(MAP_FAILED));
ASSERT_EQ(munmap(default_mmap_heap_address, kPageSize), 0);
void* brk_heap_address = sbrk(0);
ASSERT_NE(brk_heap_address, reinterpret_cast<void*>(-1));
ASSERT_TRUE(brk_heap_address != NULL);
// 1 MB should get us past what TCMalloc pre-allocated before initializing
// the sophisticated allocators.
size_t kAllocSize = 1<<20;
scoped_ptr<char, base::FreeDeleter> ptr(
static_cast<char*>(malloc(kAllocSize)));
ASSERT_TRUE(ptr != NULL);
// If two pointers are separated by less than 512MB, they are considered
// to be in the same area.
// Our random pointer could be anywhere within 0x3fffffffffff (46bits),
// and we are checking that it's not withing 1GB (30 bits) from two
// addresses (brk and mmap heap). We have roughly one chance out of
// 2^15 to flake.
const size_t kAreaRadius = 1<<29;
bool in_default_mmap_heap = ArePointersToSameArea(
ptr.get(), default_mmap_heap_address, kAreaRadius);
EXPECT_FALSE(in_default_mmap_heap);
bool in_default_brk_heap = ArePointersToSameArea(
ptr.get(), brk_heap_address, kAreaRadius);
EXPECT_FALSE(in_default_brk_heap);
// In the implementation, we always mask our random addresses with
// kRandomMask, so we use it as an additional detection mechanism.
const uintptr_t kRandomMask = 0x3fffffffffffULL;
bool impossible_random_address =
reinterpret_cast<uintptr_t>(ptr.get()) & ~kRandomMask;
EXPECT_FALSE(impossible_random_address);
}
#endif // defined(OS_LINUX) && defined(__x86_64__)
} // namespace