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/*
* Copyright (C) 2020 The Android Open Source Project
*
* 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 "libdebuggerd/scudo.h"
#include "libdebuggerd/gwp_asan.h"
#include "unwindstack/Memory.h"
#include "unwindstack/Unwinder.h"
#include <bionic/macros.h>
std::unique_ptr<char[]> AllocAndReadFully(unwindstack::Memory* process_memory, uint64_t addr,
size_t size) {
auto buf = std::make_unique<char[]>(size);
if (!process_memory->ReadFully(addr, buf.get(), size)) {
return std::unique_ptr<char[]>();
}
return buf;
}
static const uintptr_t kTagGranuleSize = 16;
ScudoCrashData::ScudoCrashData(unwindstack::Memory* process_memory,
const ProcessInfo& process_info) {
if (!process_info.has_fault_address) {
return;
}
auto stack_depot = AllocAndReadFully(process_memory, process_info.scudo_stack_depot,
__scudo_get_stack_depot_size());
auto region_info = AllocAndReadFully(process_memory, process_info.scudo_region_info,
__scudo_get_region_info_size());
auto ring_buffer = AllocAndReadFully(process_memory, process_info.scudo_ring_buffer,
__scudo_get_ring_buffer_size());
untagged_fault_addr_ = process_info.untagged_fault_address;
uintptr_t fault_page = untagged_fault_addr_ & ~(PAGE_SIZE - 1);
uintptr_t memory_begin = fault_page - PAGE_SIZE * 16;
if (memory_begin > fault_page) {
return;
}
uintptr_t memory_end = fault_page + PAGE_SIZE * 16;
if (memory_end < fault_page) {
return;
}
auto memory = std::make_unique<char[]>(memory_end - memory_begin);
for (auto i = memory_begin; i != memory_end; i += PAGE_SIZE) {
process_memory->ReadFully(i, memory.get() + i - memory_begin, PAGE_SIZE);
}
auto memory_tags = std::make_unique<char[]>((memory_end - memory_begin) / kTagGranuleSize);
for (auto i = memory_begin; i != memory_end; i += kTagGranuleSize) {
memory_tags[(i - memory_begin) / kTagGranuleSize] = process_memory->ReadTag(i);
}
__scudo_get_error_info(&error_info_, process_info.maybe_tagged_fault_address, stack_depot.get(),
region_info.get(), ring_buffer.get(), memory.get(), memory_tags.get(),
memory_begin, memory_end - memory_begin);
}
bool ScudoCrashData::CrashIsMine() const {
return error_info_.reports[0].error_type != UNKNOWN;
}
void ScudoCrashData::DumpCause(log_t* log, unwindstack::Unwinder* unwinder) const {
if (error_info_.reports[1].error_type != UNKNOWN) {
_LOG(log, logtype::HEADER,
"\nNote: multiple potential causes for this crash were detected, listing them in "
"decreasing order of probability.\n");
}
size_t report_num = 0;
while (report_num < sizeof(error_info_.reports) / sizeof(error_info_.reports[0]) &&
error_info_.reports[report_num].error_type != UNKNOWN) {
DumpReport(&error_info_.reports[report_num++], log, unwinder);
}
}
void ScudoCrashData::DumpReport(const scudo_error_report* report, log_t* log,
unwindstack::Unwinder* unwinder) const {
const char *error_type_str;
switch (report->error_type) {
case USE_AFTER_FREE:
error_type_str = "Use After Free";
break;
case BUFFER_OVERFLOW:
error_type_str = "Buffer Overflow";
break;
case BUFFER_UNDERFLOW:
error_type_str = "Buffer Underflow";
break;
default:
error_type_str = "Unknown";
break;
}
uintptr_t diff;
const char* location_str;
if (untagged_fault_addr_ < report->allocation_address) {
// Buffer Underflow, 6 bytes left of a 41-byte allocation at 0xdeadbeef.
location_str = "left of";
diff = report->allocation_address - untagged_fault_addr_;
} else if (untagged_fault_addr_ - report->allocation_address < report->allocation_size) {
// Use After Free, 40 bytes into a 41-byte allocation at 0xdeadbeef.
location_str = "into";
diff = untagged_fault_addr_ - report->allocation_address;
} else {
// Buffer Overflow, 6 bytes right of a 41-byte allocation at 0xdeadbeef.
location_str = "right of";
diff = untagged_fault_addr_ - report->allocation_address - report->allocation_size;
}
// Suffix of 'bytes', i.e. 4 bytes' vs. '1 byte'.
const char* byte_suffix = "s";
if (diff == 1) {
byte_suffix = "";
}
_LOG(log, logtype::HEADER,
"\nCause: [MTE]: %s, %" PRIuPTR " byte%s %s a %zu-byte allocation at 0x%" PRIxPTR "\n",
error_type_str, diff, byte_suffix, location_str, report->allocation_size,
report->allocation_address);
if (report->allocation_trace[0]) {
_LOG(log, logtype::BACKTRACE, "\nallocated by thread %u:\n", report->allocation_tid);
unwinder->SetDisplayBuildID(true);
for (size_t i = 0; i < 64 && report->allocation_trace[i]; ++i) {
unwindstack::FrameData frame_data =
unwinder->BuildFrameFromPcOnly(report->allocation_trace[i]);
frame_data.num = i;
_LOG(log, logtype::BACKTRACE, " %s\n", unwinder->FormatFrame(frame_data).c_str());
}
}
if (report->deallocation_trace[0]) {
_LOG(log, logtype::BACKTRACE, "\ndeallocated by thread %u:\n", report->deallocation_tid);
unwinder->SetDisplayBuildID(true);
for (size_t i = 0; i < 64 && report->deallocation_trace[i]; ++i) {
unwindstack::FrameData frame_data =
unwinder->BuildFrameFromPcOnly(report->deallocation_trace[i]);
frame_data.num = i;
_LOG(log, logtype::BACKTRACE, " %s\n", unwinder->FormatFrame(frame_data).c_str());
}
}
}
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