crashpad/util/linux/process_memory_test.cc
Mark Mentovai 984749479f Introduce FromPointerCast<>(), with defined sign/zero-extension behavior
Some of the new Linux/Android tests were failing in 32-bit code where
pointers were being casted via reinterpret_cast<>() to LinuxVMAddress,
an unsigned 64-bit type. The behavior of such casts is
implementation-defined, and in this case, sign-extension was being used
to convert the 32-bit pointers to 64 bits, resulting in very large
(unsigned) LinuxVMAddress values that could not possibly refer to proper
addresses in a 32-bit process’ address space.

The offending reinterpret_cast<>() conversions have been replaced with
the new FromPointerCast<>(), which is careful to do sign-extension when
converting to a signed type, and zero-extension when converting to an
unsigned type like LinuxVMAddress.

Bug: crashpad:30
Test: crashpad_util_test FromPointerCast*:MemoryMap.*:ProcessMemory.*
Change-Id: I6f1408dc63369a8740ecd6015d657e4407a7c271
Reviewed-on: https://chromium-review.googlesource.com/488264
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
2017-04-27 19:42:25 +00:00

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// Copyright 2017 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "util/linux/process_memory.h"
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
#include <memory>
#include "gtest/gtest.h"
#include "test/errors.h"
#include "test/multiprocess.h"
#include "util/file/file_io.h"
#include "util/misc/from_pointer_cast.h"
#include "util/posix/scoped_mmap.h"
namespace crashpad {
namespace test {
namespace {
class TargetProcessTest : public Multiprocess {
public:
TargetProcessTest() : Multiprocess() {}
~TargetProcessTest() {}
void RunAgainstSelf() { DoTest(getpid()); }
void RunAgainstForked() { Run(); }
private:
void MultiprocessParent() override { DoTest(ChildPID()); }
void MultiprocessChild() override { CheckedReadFileAtEOF(ReadPipeHandle()); }
virtual void DoTest(pid_t pid) = 0;
DISALLOW_COPY_AND_ASSIGN(TargetProcessTest);
};
class ReadTest : public TargetProcessTest {
public:
ReadTest()
: TargetProcessTest(),
page_size_(getpagesize()),
region_size_(4 * page_size_),
region_(new char[region_size_]) {
for (size_t index = 0; index < region_size_; ++index) {
region_[index] = index % 256;
}
}
private:
void DoTest(pid_t pid) override {
ProcessMemory memory;
ASSERT_TRUE(memory.Initialize(pid));
LinuxVMAddress address = FromPointerCast<LinuxVMAddress>(region_.get());
std::unique_ptr<char[]> result(new char[region_size_]);
// Ensure that the entire region can be read.
ASSERT_TRUE(memory.Read(address, region_size_, result.get()));
EXPECT_EQ(memcmp(region_.get(), result.get(), region_size_), 0);
// Ensure that a read of length 0 succeeds and doesnt touch the result.
memset(result.get(), '\0', region_size_);
ASSERT_TRUE(memory.Read(address, 0, result.get()));
for (size_t i = 0; i < region_size_; ++i) {
EXPECT_EQ(result[i], 0);
}
// Ensure that a read starting at an unaligned address works.
ASSERT_TRUE(memory.Read(address + 1, region_size_ - 1, result.get()));
EXPECT_EQ(memcmp(region_.get() + 1, result.get(), region_size_ - 1), 0);
// Ensure that a read ending at an unaligned address works.
ASSERT_TRUE(memory.Read(address, region_size_ - 1, result.get()));
EXPECT_EQ(memcmp(region_.get(), result.get(), region_size_ - 1), 0);
// Ensure that a read starting and ending at unaligned addresses works.
ASSERT_TRUE(memory.Read(address + 1, region_size_ - 2, result.get()));
EXPECT_EQ(memcmp(region_.get() + 1, result.get(), region_size_ - 2), 0);
// Ensure that a read of exactly one page works.
ASSERT_TRUE(memory.Read(address + page_size_, page_size_, result.get()));
EXPECT_EQ(memcmp(region_.get() + page_size_, result.get(), page_size_), 0);
// Ensure that reading exactly a single byte works.
result[1] = 'J';
ASSERT_TRUE(memory.Read(address + 2, 1, result.get()));
EXPECT_EQ(result[0], region_[2]);
EXPECT_EQ(result[1], 'J');
}
const size_t page_size_;
const size_t region_size_;
std::unique_ptr<char[]> region_;
DISALLOW_COPY_AND_ASSIGN(ReadTest);
};
TEST(ProcessMemory, ReadSelf) {
ReadTest test;
test.RunAgainstSelf();
}
TEST(ProcessMemory, ReadForked) {
ReadTest test;
test.RunAgainstForked();
}
bool ReadCString(const ProcessMemory& memory,
const char* pointer,
std::string* result) {
return memory.ReadCString(FromPointerCast<LinuxVMAddress>(pointer), result);
}
bool ReadCStringSizeLimited(const ProcessMemory& memory,
const char* pointer,
size_t size,
std::string* result) {
return memory.ReadCStringSizeLimited(
FromPointerCast<LinuxVMAddress>(pointer), size, result);
}
const char kConstCharEmpty[] = "";
const char kConstCharShort[] = "A short const char[]";
class ReadCStringTest : public TargetProcessTest {
public:
ReadCStringTest(bool limit_size)
: TargetProcessTest(),
member_char_empty_(""),
member_char_short_("A short member char[]"),
limit_size_(limit_size) {
const size_t kStringLongSize = 4 * getpagesize();
for (size_t index = 0; index < kStringLongSize; ++index) {
string_long_.push_back((index % 255) + 1);
}
EXPECT_EQ(string_long_.size(), kStringLongSize);
}
private:
void DoTest(pid_t pid) override {
ProcessMemory memory;
ASSERT_TRUE(memory.Initialize(pid));
std::string result;
if (limit_size_) {
ASSERT_TRUE(ReadCStringSizeLimited(
memory, kConstCharEmpty, arraysize(kConstCharEmpty), &result));
EXPECT_EQ(result, kConstCharEmpty);
ASSERT_TRUE(ReadCStringSizeLimited(
memory, kConstCharShort, arraysize(kConstCharShort), &result));
EXPECT_EQ(result, kConstCharShort);
EXPECT_FALSE(ReadCStringSizeLimited(
memory, kConstCharShort, arraysize(kConstCharShort) - 1, &result));
ASSERT_TRUE(ReadCStringSizeLimited(
memory, member_char_empty_, strlen(member_char_empty_) + 1, &result));
EXPECT_EQ(result, member_char_empty_);
ASSERT_TRUE(ReadCStringSizeLimited(
memory, member_char_short_, strlen(member_char_short_) + 1, &result));
EXPECT_EQ(result, member_char_short_);
EXPECT_FALSE(ReadCStringSizeLimited(
memory, member_char_short_, strlen(member_char_short_), &result));
ASSERT_TRUE(ReadCStringSizeLimited(
memory, string_long_.c_str(), string_long_.size() + 1, &result));
EXPECT_EQ(result, string_long_);
EXPECT_FALSE(ReadCStringSizeLimited(
memory, string_long_.c_str(), string_long_.size(), &result));
} else {
ASSERT_TRUE(ReadCString(memory, kConstCharEmpty, &result));
EXPECT_EQ(result, kConstCharEmpty);
ASSERT_TRUE(ReadCString(memory, kConstCharShort, &result));
EXPECT_EQ(result, kConstCharShort);
ASSERT_TRUE(ReadCString(memory, member_char_empty_, &result));
EXPECT_EQ(result, member_char_empty_);
ASSERT_TRUE(ReadCString(memory, member_char_short_, &result));
EXPECT_EQ(result, member_char_short_);
ASSERT_TRUE(ReadCString(memory, string_long_.c_str(), &result));
EXPECT_EQ(result, string_long_);
}
}
std::string string_long_;
const char* member_char_empty_;
const char* member_char_short_;
const bool limit_size_;
DISALLOW_COPY_AND_ASSIGN(ReadCStringTest);
};
TEST(ProcessMemory, ReadCStringSelf) {
ReadCStringTest test(/* limit_size= */ false);
test.RunAgainstSelf();
}
TEST(ProcessMemory, ReadCStringForked) {
ReadCStringTest test(/* limit_size= */ false);
test.RunAgainstForked();
}
TEST(ProcessMemory, ReadCStringSizeLimitedSelf) {
ReadCStringTest test(/* limit_size= */ true);
test.RunAgainstSelf();
}
TEST(ProcessMemory, ReadCStringSizeLimitedForked) {
ReadCStringTest test(/* limit_size= */ true);
test.RunAgainstForked();
}
class ReadUnmappedTest : public TargetProcessTest {
public:
ReadUnmappedTest()
: TargetProcessTest(),
page_size_(getpagesize()),
region_size_(2 * page_size_),
result_(new char[region_size_]) {
if (!pages_.ResetMmap(nullptr,
region_size_,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS,
-1,
0)) {
ADD_FAILURE();
return;
}
char* region = pages_.addr_as<char*>();
for (size_t index = 0; index < region_size_; ++index) {
region[index] = index % 256;
}
EXPECT_TRUE(pages_.ResetAddrLen(region, page_size_));
}
private:
void DoTest(pid_t pid) override {
ProcessMemory memory;
ASSERT_TRUE(memory.Initialize(pid));
LinuxVMAddress page_addr1 = pages_.addr_as<LinuxVMAddress>();
LinuxVMAddress page_addr2 = page_addr1 + page_size_;
EXPECT_TRUE(memory.Read(page_addr1, page_size_, result_.get()));
EXPECT_TRUE(memory.Read(page_addr2 - 1, 1, result_.get()));
EXPECT_FALSE(memory.Read(page_addr1, region_size_, result_.get()));
EXPECT_FALSE(memory.Read(page_addr2, page_size_, result_.get()));
EXPECT_FALSE(memory.Read(page_addr2 - 1, 2, result_.get()));
}
ScopedMmap pages_;
const size_t page_size_;
const size_t region_size_;
std::unique_ptr<char[]> result_;
DISALLOW_COPY_AND_ASSIGN(ReadUnmappedTest);
};
TEST(ProcessMemory, ReadUnmappedSelf) {
ReadUnmappedTest test;
ASSERT_FALSE(testing::Test::HasFailure());
test.RunAgainstSelf();
}
TEST(ProcessMemory, ReadUnmappedForked) {
ReadUnmappedTest test;
ASSERT_FALSE(testing::Test::HasFailure());
test.RunAgainstForked();
}
class ReadCStringUnmappedTest : public TargetProcessTest {
public:
ReadCStringUnmappedTest(bool limit_size)
: TargetProcessTest(),
page_size_(getpagesize()),
region_size_(2 * page_size_),
limit_size_(limit_size) {
if (!pages_.ResetMmap(nullptr,
region_size_,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS,
-1,
0)) {
ADD_FAILURE();
return;
}
char* region = pages_.addr_as<char*>();
for (size_t index = 0; index < region_size_; ++index) {
region[index] = 1 + index % 255;
}
// A string at the start of the mapped region
string1_ = region;
string1_[expected_length_] = '\0';
// A string near the end of the mapped region
string2_ = region + page_size_ - expected_length_ * 2;
string2_[expected_length_] = '\0';
// A string that crosses from the mapped into the unmapped region
string3_ = region + page_size_ - expected_length_ + 1;
string3_[expected_length_] = '\0';
// A string entirely in the unmapped region
string4_ = region + page_size_ + 10;
string4_[expected_length_] = '\0';
result_.reserve(expected_length_ + 1);
EXPECT_TRUE(pages_.ResetAddrLen(region, page_size_));
}
private:
void DoTest(pid_t pid) {
ProcessMemory memory;
ASSERT_TRUE(memory.Initialize(pid));
if (limit_size_) {
ASSERT_TRUE(ReadCStringSizeLimited(
memory, string1_, expected_length_ + 1, &result_));
EXPECT_EQ(result_, string1_);
ASSERT_TRUE(ReadCStringSizeLimited(
memory, string2_, expected_length_ + 1, &result_));
EXPECT_EQ(result_, string2_);
EXPECT_FALSE(ReadCStringSizeLimited(
memory, string3_, expected_length_ + 1, &result_));
EXPECT_FALSE(ReadCStringSizeLimited(
memory, string4_, expected_length_ + 1, &result_));
} else {
ASSERT_TRUE(ReadCString(memory, string1_, &result_));
EXPECT_EQ(result_, string1_);
ASSERT_TRUE(ReadCString(memory, string2_, &result_));
EXPECT_EQ(result_, string2_);
EXPECT_FALSE(ReadCString(memory, string3_, &result_));
EXPECT_FALSE(ReadCString(memory, string4_, &result_));
}
}
std::string result_;
ScopedMmap pages_;
const size_t page_size_;
const size_t region_size_;
static const size_t expected_length_ = 10;
char* string1_;
char* string2_;
char* string3_;
char* string4_;
const bool limit_size_;
DISALLOW_COPY_AND_ASSIGN(ReadCStringUnmappedTest);
};
TEST(ProcessMemory, ReadCStringUnmappedSelf) {
ReadCStringUnmappedTest test(/* limit_size= */ false);
ASSERT_FALSE(testing::Test::HasFailure());
test.RunAgainstSelf();
}
TEST(ProcessMemory, ReadCStringUnmappedForked) {
ReadCStringUnmappedTest test(/* limit_size= */ false);
ASSERT_FALSE(testing::Test::HasFailure());
test.RunAgainstForked();
}
TEST(ProcessMemory, ReadCStringSizeLimitedUnmappedSelf) {
ReadCStringUnmappedTest test(/* limit_size= */ true);
ASSERT_FALSE(testing::Test::HasFailure());
test.RunAgainstSelf();
}
TEST(ProcessMemory, ReadCStringSizeLimitedUnmappedForked) {
ReadCStringUnmappedTest test(/* limit_size= */ true);
ASSERT_FALSE(testing::Test::HasFailure());
test.RunAgainstForked();
}
} // namespace
} // namespace test
} // namespace crashpad