crashpad/snapshot/elf/elf_dynamic_array_reader.cc
Joshua Peraza 8bbe985004 elf: Use d_ptr instead of d_val when reading from a dynamic array
The dynamic array reader should treat data as unsigned when initially
reading values from the array to prevent premature sign-extension. The
glibc and traditional android headers define d_val using Elf32_Word, an
unsigned type. linux/elf.h, used by unified android headers, defines
d_val using Elf32_Sword, a signed type. Use d_ptr instead since it's
always an unsigned type.

Bug: crashpad:30
Change-Id: Ie8e88941fefc7075621aefe226fdba33b1f6129c
Reviewed-on: https://chromium-review.googlesource.com/847818
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
2018-01-08 23:28:21 +00:00

84 lines
2.6 KiB
C++

// 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_dynamic_array_reader.h"
#include <elf.h>
#include <type_traits>
#include "util/stdlib/map_insert.h"
namespace crashpad {
namespace {
template <typename DynType>
bool Read(const ProcessMemoryRange& memory,
VMAddress address,
VMSize size,
std::map<uint64_t, uint64_t>* values) {
std::map<uint64_t, uint64_t> local_values;
while (size > 0) {
DynType entry;
if (!memory.Read(address, sizeof(entry), &entry)) {
return false;
}
size -= sizeof(entry);
address += sizeof(entry);
switch (entry.d_tag) {
case DT_NULL:
values->swap(local_values);
if (size != 0) {
LOG(WARNING) << size << " trailing bytes not read";
}
return true;
case DT_NEEDED:
// Skip these entries for now.
break;
default:
static_assert(std::is_unsigned<decltype(entry.d_un.d_ptr)>::value,
"type must be unsigned");
static_assert(static_cast<void*>(&entry.d_un.d_ptr) ==
static_cast<void*>(&entry.d_un.d_val) &&
sizeof(entry.d_un.d_ptr) == sizeof(entry.d_un.d_val),
"d_ptr and d_val must be aliases");
if (!MapInsertOrReplace(
&local_values, entry.d_tag, entry.d_un.d_ptr, nullptr)) {
LOG(ERROR) << "duplicate dynamic array entry";
return false;
}
}
}
LOG(ERROR) << "missing DT_NULL";
return false;
}
} // namespace
ElfDynamicArrayReader::ElfDynamicArrayReader() : values_() {}
ElfDynamicArrayReader::~ElfDynamicArrayReader() {}
bool ElfDynamicArrayReader::Initialize(const ProcessMemoryRange& memory,
VMAddress address,
VMSize size) {
return memory.Is64Bit() ? Read<Elf64_Dyn>(memory, address, size, &values_)
: Read<Elf32_Dyn>(memory, address, size, &values_);
}
} // namespace crashpad