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crashpad/snapshot/elf/elf_image_reader.cc
Scott Graham ee1d5124a2 Fix incorrect range checks in elf image note reader 
Overflows before and after padding could cause the max note size check
to be evaded.

Bug: chromium:967228, chromium: 967257, chromium:967223
Change-Id: I499a273e76e78529fc59ddcb74055be6d01fa2cb
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/1631635
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
Commit-Queue: Scott Graham <scottmg@chromium.org>
2019-05-28 18:23:11 +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 "snapshot/elf/elf_image_reader.h"
#include <stddef.h>
#include <algorithm>
#include <limits>
#include <utility>
#include <vector>
#include "base/logging.h"
#include "base/numerics/safe_math.h"
#include "build/build_config.h"
#include "util/numeric/checked_vm_address_range.h"
namespace crashpad {
class ElfImageReader::ProgramHeaderTable {
public:
virtual ~ProgramHeaderTable() {}
virtual bool VerifyLoadSegments(bool verbose) const = 0;
virtual size_t Size() const = 0;
virtual bool GetDynamicSegment(VMAddress* address, VMSize* size) const = 0;
virtual bool GetPreferredElfHeaderAddress(VMAddress* address,
bool verbose) const = 0;
virtual bool GetPreferredLoadedMemoryRange(VMAddress* address,
VMSize* size,
bool verbose) const = 0;
// Locate the next PT_NOTE segment starting at segment index start_index. If a
// PT_NOTE segment is found, start_index is set to the next index after the
// found segment.
virtual bool GetNoteSegment(size_t* start_index,
VMAddress* address,
VMSize* size) const = 0;
protected:
ProgramHeaderTable() {}
};
template <typename PhdrType>
class ElfImageReader::ProgramHeaderTableSpecific
: public ElfImageReader::ProgramHeaderTable {
public:
ProgramHeaderTableSpecific<PhdrType>() {}
~ProgramHeaderTableSpecific<PhdrType>() {}
bool Initialize(const ProcessMemoryRange& memory,
VMAddress address,
VMSize num_segments,
bool verbose) {
INITIALIZATION_STATE_SET_INITIALIZING(initialized_);
table_.resize(num_segments);
if (!memory.Read(address, sizeof(PhdrType) * num_segments, table_.data())) {
return false;
}
if (!VerifyLoadSegments(verbose)) {
return false;
}
INITIALIZATION_STATE_SET_VALID(initialized_);
return true;
}
bool VerifyLoadSegments(bool verbose) const override {
constexpr bool is_64_bit = std::is_same<PhdrType, Elf64_Phdr>::value;
VMAddress last_vaddr;
bool load_found = false;
for (const auto& header : table_) {
if (header.p_type == PT_LOAD) {
CheckedVMAddressRange load_range(
is_64_bit, header.p_vaddr, header.p_memsz);
if (!load_range.IsValid()) {
LOG_IF(ERROR, verbose) << "bad load range";
return false;
}
if (load_found && header.p_vaddr <= last_vaddr) {
LOG_IF(ERROR, verbose) << "out of order load segments";
return false;
}
load_found = true;
last_vaddr = header.p_vaddr;
}
}
return true;
}
size_t Size() const override { return sizeof(PhdrType) * table_.size(); }
bool GetPreferredElfHeaderAddress(VMAddress* address,
bool verbose) const override {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
for (const auto& header : table_) {
if (header.p_type == PT_LOAD && header.p_offset == 0) {
*address = header.p_vaddr;
return true;
}
}
LOG_IF(ERROR, verbose) << "no preferred header address";
return false;
}
bool GetPreferredLoadedMemoryRange(VMAddress* base,
VMSize* size,
bool verbose) const override {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
VMAddress preferred_base = 0;
VMAddress preferred_end = 0;
bool load_found = false;
for (const auto& header : table_) {
if (header.p_type == PT_LOAD) {
if (!load_found) {
preferred_base = header.p_vaddr;
load_found = true;
}
preferred_end = header.p_vaddr + header.p_memsz;
}
}
if (load_found) {
*base = preferred_base;
*size = preferred_end - preferred_base;
return true;
}
LOG_IF(ERROR, verbose) << "no load segments";
return false;
}
bool GetDynamicSegment(VMAddress* address, VMSize* size) const override {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
const PhdrType* phdr;
if (!GetProgramHeader(PT_DYNAMIC, &phdr)) {
return false;
}
*address = phdr->p_vaddr;
*size = phdr->p_memsz;
return true;
}
bool GetProgramHeader(uint32_t type, const PhdrType** header_out) const {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
for (const auto& header : table_) {
if (header.p_type == type) {
*header_out = &header;
return true;
}
}
return false;
}
bool GetNoteSegment(size_t* start_index,
VMAddress* address,
VMSize* size) const override {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
for (size_t index = *start_index; index < table_.size(); ++index) {
if (table_[index].p_type == PT_NOTE && table_[index].p_vaddr != 0) {
*start_index = index + 1;
*address = table_[index].p_vaddr;
*size = table_[index].p_memsz;
return true;
}
}
return false;
}
private:
std::vector<PhdrType> table_;
InitializationStateDcheck initialized_;
DISALLOW_COPY_AND_ASSIGN(ProgramHeaderTableSpecific<PhdrType>);
};
ElfImageReader::NoteReader::~NoteReader() = default;
ElfImageReader::NoteReader::Result ElfImageReader::NoteReader::NextNote(
std::string* name,
NoteType* type,
std::string* desc,
VMAddress* desc_address) {
if (!is_valid_) {
LOG(ERROR) << "invalid note reader";
return Result::kError;
}
Result result = Result::kError;
do {
while (current_address_ == segment_end_address_) {
VMSize segment_size;
if (!phdr_table_->GetNoteSegment(
&phdr_index_, &current_address_, &segment_size)) {
return Result::kNoMoreNotes;
}
current_address_ += elf_reader_->GetLoadBias();
segment_end_address_ = current_address_ + segment_size;
segment_range_ = std::make_unique<ProcessMemoryRange>();
if (!segment_range_->Initialize(*range_) ||
!segment_range_->RestrictRange(current_address_, segment_size)) {
return Result::kError;
}
}
retry_ = false;
result = range_->Is64Bit()
? ReadNote<Elf64_Nhdr>(name, type, desc, desc_address)
: ReadNote<Elf32_Nhdr>(name, type, desc, desc_address);
} while (retry_);
if (result == Result::kSuccess) {
return Result::kSuccess;
}
is_valid_ = false;
return Result::kError;
}
namespace {
// The maximum size the user can specify for maximum note size. Clamping this
// ensures that buffer allocations cannot be wildly large. It is not expected
// that a note would be larger than ~1k in normal usage.
constexpr size_t kMaxMaxNoteSize = 16384;
} // namespace
ElfImageReader::NoteReader::NoteReader(const ElfImageReader* elf_reader,
const ProcessMemoryRange* range,
const ProgramHeaderTable* phdr_table,
size_t max_note_size,
const std::string& name_filter,
NoteType type_filter,
bool use_filter)
: current_address_(0),
segment_end_address_(0),
elf_reader_(elf_reader),
range_(range),
phdr_table_(phdr_table),
segment_range_(),
phdr_index_(0),
max_note_size_(std::min(kMaxMaxNoteSize, max_note_size)),
name_filter_(name_filter),
type_filter_(type_filter),
use_filter_(use_filter),
is_valid_(true),
retry_(false) {
DCHECK_LT(max_note_size, kMaxMaxNoteSize);
}
template <typename NhdrType>
ElfImageReader::NoteReader::Result ElfImageReader::NoteReader::ReadNote(
std::string* name,
NoteType* type,
std::string* desc,
VMAddress* desc_address) {
static_assert(sizeof(*type) >= sizeof(NhdrType::n_namesz),
"Note field size mismatch");
DCHECK_LT(current_address_, segment_end_address_);
NhdrType note_info;
if (!segment_range_->Read(current_address_, sizeof(note_info), &note_info)) {
return Result::kError;
}
current_address_ += sizeof(note_info);
constexpr size_t align = sizeof(note_info.n_namesz);
#define CHECKED_PAD(x, into) \
base::CheckAnd(base::CheckAdd(x, align - 1), ~(align - 1)) \
.AssignIfValid(&into)
size_t padded_namesz;
if (!CHECKED_PAD(note_info.n_namesz, padded_namesz)) {
return Result::kError;
}
size_t padded_descsz;
if (!CHECKED_PAD(note_info.n_descsz, padded_descsz)) {
return Result::kError;
}
size_t note_size;
if (!base::CheckAdd(padded_namesz, padded_descsz).AssignIfValid(&note_size)) {
return Result::kError;
}
// Notes typically have 4-byte alignment. However, .note.android.ident may
// inadvertently use 2-byte alignment.
// https://android-review.googlesource.com/c/platform/bionic/+/554986/
// We can still find .note.android.ident if it appears first in a note segment
// but there may be 4-byte aligned notes following it. If this note was
// aligned at less than 4-bytes, expect that the next note will be aligned at
// 4-bytes and add extra padding, if necessary.
VMAddress end_of_note_candidate;
if (!base::CheckAdd(current_address_, note_size)
.AssignIfValid(&end_of_note_candidate)) {
return Result::kError;
}
VMAddress end_of_note;
if (!CHECKED_PAD(end_of_note_candidate, end_of_note)) {
return Result::kError;
}
end_of_note = std::min(end_of_note, segment_end_address_);
#undef CHECKED_PAD
if (note_size > max_note_size_) {
current_address_ = end_of_note;
retry_ = true;
return Result::kError;
}
if (use_filter_ && note_info.n_type != type_filter_) {
current_address_ = end_of_note;
retry_ = true;
return Result::kError;
}
std::string local_name(note_info.n_namesz, '\0');
if (!segment_range_->Read(
current_address_, note_info.n_namesz, &local_name[0])) {
return Result::kError;
}
if (!local_name.empty()) {
if (local_name.back() != '\0') {
LOG(ERROR) << "unterminated note name";
return Result::kError;
}
local_name.pop_back();
}
if (use_filter_ && local_name != name_filter_) {
current_address_ = end_of_note;
retry_ = true;
return Result::kError;
}
current_address_ += padded_namesz;
std::string local_desc(note_info.n_descsz, '\0');
if (!segment_range_->Read(
current_address_, note_info.n_descsz, &local_desc[0])) {
return Result::kError;
}
*desc_address = current_address_;
current_address_ = end_of_note;
if (name) {
name->swap(local_name);
}
if (type) {
*type = note_info.n_type;
}
desc->swap(local_desc);
return Result::kSuccess;
}
ElfImageReader::ElfImageReader()
: header_64_(),
ehdr_address_(0),
load_bias_(0),
memory_(),
program_headers_(),
dynamic_array_(),
symbol_table_(),
initialized_(),
dynamic_array_initialized_(),
symbol_table_initialized_() {}
ElfImageReader::~ElfImageReader() {}
bool ElfImageReader::Initialize(const ProcessMemoryRange& memory,
VMAddress address,
bool verbose) {
INITIALIZATION_STATE_SET_INITIALIZING(initialized_);
ehdr_address_ = address;
if (!memory_.Initialize(memory)) {
return false;
}
uint8_t e_ident[EI_NIDENT];
if (!memory_.Read(ehdr_address_, EI_NIDENT, e_ident)) {
return false;
}
if (e_ident[EI_MAG0] != ELFMAG0 || e_ident[EI_MAG1] != ELFMAG1 ||
e_ident[EI_MAG2] != ELFMAG2 || e_ident[EI_MAG3] != ELFMAG3) {
LOG_IF(ERROR, verbose) << "Incorrect ELF magic number";
return false;
}
if (!(memory_.Is64Bit() && e_ident[EI_CLASS] == ELFCLASS64) &&
!(!memory_.Is64Bit() && e_ident[EI_CLASS] == ELFCLASS32)) {
LOG_IF(ERROR, verbose) << "unexpected bitness";
return false;
}
#if defined(ARCH_CPU_LITTLE_ENDIAN)
constexpr uint8_t expected_encoding = ELFDATA2LSB;
#elif defined(ARCH_CPU_BIG_ENDIAN)
constexpr uint8_t expected_encoding = ELFDATA2MSB;
#endif
if (e_ident[EI_DATA] != expected_encoding) {
LOG_IF(ERROR, verbose) << "unexpected encoding";
return false;
}
if (e_ident[EI_VERSION] != EV_CURRENT) {
LOG_IF(ERROR, verbose) << "unexpected version";
return false;
}
if (!(memory_.Is64Bit()
? memory_.Read(ehdr_address_, sizeof(header_64_), &header_64_)
: memory_.Read(ehdr_address_, sizeof(header_32_), &header_32_))) {
return false;
}
#define VERIFY_HEADER(header) \
do { \
if (header.e_type != ET_EXEC && header.e_type != ET_DYN) { \
LOG_IF(ERROR, verbose) << "unexpected image type"; \
return false; \
} \
if (header.e_version != EV_CURRENT) { \
LOG_IF(ERROR, verbose) << "unexpected version"; \
return false; \
} \
if (header.e_ehsize != sizeof(header)) { \
LOG_IF(ERROR, verbose) << "unexpected header size"; \
return false; \
} \
} while (false);
if (memory_.Is64Bit()) {
VERIFY_HEADER(header_64_);
} else {
VERIFY_HEADER(header_32_);
}
if (!InitializeProgramHeaders(verbose)) {
return false;
}
VMAddress preferred_ehdr_address;
if (!program_headers_.get()->GetPreferredElfHeaderAddress(
&preferred_ehdr_address, verbose)) {
return false;
}
load_bias_ = ehdr_address_ - preferred_ehdr_address;
VMAddress base_address;
VMSize loaded_size;
if (!program_headers_.get()->GetPreferredLoadedMemoryRange(
&base_address, &loaded_size, verbose)) {
return false;
}
base_address += load_bias_;
if (!memory_.RestrictRange(base_address, loaded_size)) {
return false;
}
VMSize ehdr_size;
VMAddress phdr_address;
if (memory_.Is64Bit()) {
ehdr_size = sizeof(header_64_);
phdr_address = ehdr_address_ + header_64_.e_phoff;
} else {
ehdr_size = sizeof(header_32_);
phdr_address = ehdr_address_ + header_32_.e_phoff;
}
CheckedVMAddressRange range(memory_.Is64Bit(), base_address, loaded_size);
if (!range.ContainsRange(
CheckedVMAddressRange(memory_.Is64Bit(), ehdr_address_, ehdr_size))) {
LOG_IF(ERROR, verbose) << "ehdr out of range";
return false;
}
if (!range.ContainsRange(CheckedVMAddressRange(
memory.Is64Bit(), phdr_address, program_headers_->Size()))) {
LOG_IF(ERROR, verbose) << "phdrs out of range";
return false;
}
INITIALIZATION_STATE_SET_VALID(initialized_);
return true;
}
uint16_t ElfImageReader::FileType() const {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
return memory_.Is64Bit() ? header_64_.e_type : header_32_.e_type;
}
bool ElfImageReader::SoName(std::string* name) {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
if (!InitializeDynamicArray()) {
return false;
}
VMSize offset;
if (!dynamic_array_->GetValue(DT_SONAME, true, &offset)) {
return false;
}
return ReadDynamicStringTableAtOffset(offset, name);
}
bool ElfImageReader::GetDynamicSymbol(const std::string& name,
VMAddress* address,
VMSize* size) {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
if (!InitializeDynamicSymbolTable()) {
return false;
}
ElfSymbolTableReader::SymbolInformation info;
if (!symbol_table_->GetSymbol(name, &info)) {
return false;
}
if (info.shndx == SHN_UNDEF || info.shndx == SHN_COMMON) {
return false;
}
switch (info.binding) {
case STB_GLOBAL:
case STB_WEAK:
break;
case STB_LOCAL:
default:
return false;
}
switch (info.type) {
case STT_OBJECT:
case STT_FUNC:
break;
case STT_COMMON:
case STT_NOTYPE:
case STT_SECTION:
case STT_FILE:
case STT_TLS:
default:
return false;
}
if (info.shndx != SHN_ABS) {
info.address += GetLoadBias();
}
*address = info.address;
*size = info.size;
return true;
}
bool ElfImageReader::ReadDynamicStringTableAtOffset(VMSize offset,
std::string* string) {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
if (!InitializeDynamicArray()) {
return false;
}
VMAddress string_table_address;
VMSize string_table_size;
if (!GetAddressFromDynamicArray(DT_STRTAB, true, &string_table_address) ||
!dynamic_array_->GetValue(DT_STRSZ, true, &string_table_size)) {
LOG(ERROR) << "missing string table info";
return false;
}
if (offset >= string_table_size) {
LOG(ERROR) << "bad offset";
return false;
}
if (!memory_.ReadCStringSizeLimited(
string_table_address + offset, string_table_size - offset, string)) {
LOG(ERROR) << "missing nul-terminator";
return false;
}
return true;
}
bool ElfImageReader::GetDebugAddress(VMAddress* debug) {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
if (!InitializeDynamicArray()) {
return false;
}
return GetAddressFromDynamicArray(DT_DEBUG, true, debug);
}
bool ElfImageReader::GetDynamicArrayAddress(VMAddress* address) {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
VMAddress dyn_segment_address;
VMSize dyn_segment_size;
if (!program_headers_.get()->GetDynamicSegment(&dyn_segment_address,
&dyn_segment_size)) {
LOG(ERROR) << "no dynamic segment";
return false;
}
*address = dyn_segment_address + GetLoadBias();
return true;
}
VMAddress ElfImageReader::GetProgramHeaderTableAddress() {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
return ehdr_address_ +
(memory_.Is64Bit() ? header_64_.e_phoff : header_32_.e_phoff);
}
bool ElfImageReader::InitializeProgramHeaders(bool verbose) {
#define INITIALIZE_PROGRAM_HEADERS(PhdrType, header) \
do { \
if (header.e_phentsize != sizeof(PhdrType)) { \
LOG_IF(ERROR, verbose) << "unexpected phdr size"; \
return false; \
} \
auto phdrs = new ProgramHeaderTableSpecific<PhdrType>(); \
program_headers_.reset(phdrs); \
if (!phdrs->Initialize(memory_, \
ehdr_address_ + header.e_phoff, \
header.e_phnum, \
verbose)) { \
return false; \
} \
} while (false);
if (memory_.Is64Bit()) {
INITIALIZE_PROGRAM_HEADERS(Elf64_Phdr, header_64_);
} else {
INITIALIZE_PROGRAM_HEADERS(Elf32_Phdr, header_32_);
}
return true;
}
bool ElfImageReader::InitializeDynamicArray() {
if (dynamic_array_initialized_.is_valid()) {
return true;
}
if (!dynamic_array_initialized_.is_uninitialized()) {
return false;
}
dynamic_array_initialized_.set_invalid();
VMAddress dyn_segment_address;
VMSize dyn_segment_size;
if (!program_headers_.get()->GetDynamicSegment(&dyn_segment_address,
&dyn_segment_size)) {
LOG(ERROR) << "no dynamic segment";
return false;
}
dyn_segment_address += GetLoadBias();
dynamic_array_.reset(new ElfDynamicArrayReader());
if (!dynamic_array_->Initialize(
memory_, dyn_segment_address, dyn_segment_size)) {
return false;
}
dynamic_array_initialized_.set_valid();
return true;
}
bool ElfImageReader::InitializeDynamicSymbolTable() {
if (symbol_table_initialized_.is_valid()) {
return true;
}
if (!symbol_table_initialized_.is_uninitialized()) {
return false;
}
symbol_table_initialized_.set_invalid();
if (!InitializeDynamicArray()) {
return false;
}
VMAddress symbol_table_address;
if (!GetAddressFromDynamicArray(DT_SYMTAB, true, &symbol_table_address)) {
LOG(ERROR) << "no symbol table";
return false;
}
// Try both DT_HASH and DT_GNU_HASH. They're completely different, but both
// circuitously offer a way to find the number of entries in the symbol table.
// DT_HASH is specifically checked first, because depending on the linker, the
// count maybe be incorrect for zero-export cases. In practice, it is believed
// that the zero-export case is probably not particularly useful, so this
// incorrect count will only occur in constructed test cases (see
// ElfImageReader.DtHashAndDtGnuHashMatch).
VMSize number_of_symbol_table_entries;
if (!GetNumberOfSymbolEntriesFromDtHash(&number_of_symbol_table_entries) &&
!GetNumberOfSymbolEntriesFromDtGnuHash(&number_of_symbol_table_entries)) {
LOG(ERROR) << "could not retrieve number of symbol table entries";
return false;
}
symbol_table_.reset(new ElfSymbolTableReader(
&memory_, this, symbol_table_address, number_of_symbol_table_entries));
symbol_table_initialized_.set_valid();
return true;
}
bool ElfImageReader::GetAddressFromDynamicArray(uint64_t tag,
bool log,
VMAddress* address) {
if (!dynamic_array_->GetValue(tag, log, address)) {
return false;
}
#if defined(OS_ANDROID) || defined(OS_FUCHSIA)
// The GNU loader updates the dynamic array according to the load bias.
// The Android and Fuchsia loaders only update the debug address.
if (tag != DT_DEBUG) {
*address += GetLoadBias();
}
#endif // OS_ANDROID
return true;
}
bool ElfImageReader::GetNumberOfSymbolEntriesFromDtHash(
VMSize* number_of_symbol_table_entries) {
if (!InitializeDynamicArray()) {
return false;
}
VMAddress dt_hash_address;
if (!GetAddressFromDynamicArray(DT_HASH, false, &dt_hash_address)) {
return false;
}
struct {
uint32_t nbucket;
uint32_t nchain;
} header;
if (!memory_.Read(dt_hash_address, sizeof(header), &header)) {
LOG(ERROR) << "failed to read DT_HASH header";
return false;
}
*number_of_symbol_table_entries = header.nchain;
return true;
}
bool ElfImageReader::GetNumberOfSymbolEntriesFromDtGnuHash(
VMSize* number_of_symbol_table_entries) {
if (!InitializeDynamicArray()) {
return false;
}
VMAddress dt_gnu_hash_address;
if (!GetAddressFromDynamicArray(DT_GNU_HASH, false, &dt_gnu_hash_address)) {
return false;
}
// See https://flapenguin.me/2017/05/10/elf-lookup-dt-gnu-hash/ and
// https://sourceware.org/ml/binutils/2006-10/msg00377.html.
struct {
uint32_t nbuckets;
uint32_t symoffset;
uint32_t bloom_size;
uint32_t bloom_shift;
} header;
if (!memory_.Read(dt_gnu_hash_address, sizeof(header), &header)) {
LOG(ERROR) << "failed to read DT_GNU_HASH header";
return false;
}
std::vector<uint32_t> buckets(header.nbuckets);
const size_t kNumBytesForBuckets = sizeof(buckets[0]) * buckets.size();
const size_t kWordSize =
memory_.Is64Bit() ? sizeof(uint64_t) : sizeof(uint32_t);
const VMAddress buckets_address =
dt_gnu_hash_address + sizeof(header) + (kWordSize * header.bloom_size);
if (!memory_.Read(buckets_address, kNumBytesForBuckets, buckets.data())) {
LOG(ERROR) << "read buckets";
return false;
}
// Locate the chain that handles the largest index bucket.
uint32_t last_symbol = 0;
for (uint32_t i = 0; i < header.nbuckets; ++i) {
last_symbol = std::max(buckets[i], last_symbol);
}
if (last_symbol < header.symoffset) {
*number_of_symbol_table_entries = header.symoffset;
return true;
}
// Walk the bucket's chain to add the chain length to the total.
const VMAddress chains_base_address = buckets_address + kNumBytesForBuckets;
for (;;) {
uint32_t chain_entry;
if (!memory_.Read(chains_base_address + (last_symbol - header.symoffset) *
sizeof(chain_entry),
sizeof(chain_entry),
&chain_entry)) {
LOG(ERROR) << "read chain entry";
return false;
}
++last_symbol;
// If the low bit is set, this entry is the end of the chain.
if (chain_entry & 1)
break;
}
*number_of_symbol_table_entries = last_symbol;
return true;
}
std::unique_ptr<ElfImageReader::NoteReader> ElfImageReader::Notes(
size_t max_note_size) {
return std::make_unique<NoteReader>(
this, &memory_, program_headers_.get(), max_note_size);
}
std::unique_ptr<ElfImageReader::NoteReader>
ElfImageReader::NotesWithNameAndType(const std::string& name,
NoteReader::NoteType type,
size_t max_note_size) {
return std::make_unique<NoteReader>(
this, &memory_, program_headers_.get(), max_note_size, name, type, true);
}
const ProcessMemoryRange* ElfImageReader::Memory() const {
return &memory_;
}
} // namespace crashpad
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