blob: ed2b974ea484dddcf1fd5deb79715dc510f395e0 [file] [log] [blame]
/*
* 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/gwp_asan.h"
#include "libdebuggerd/tombstone.h"
#include "libdebuggerd/utility.h"
#include "gwp_asan/common.h"
#include "gwp_asan/crash_handler.h"
#include <unwindstack/Maps.h>
#include <unwindstack/Memory.h>
#include <unwindstack/Regs.h>
#include <unwindstack/Unwinder.h>
#include "tombstone.pb.h"
// Retrieve GWP-ASan state from `state_addr` inside the process at
// `process_memory`. Place the state into `*state`.
static bool retrieve_gwp_asan_state(unwindstack::Memory* process_memory, uintptr_t state_addr,
gwp_asan::AllocatorState* state) {
return process_memory->ReadFully(state_addr, state, sizeof(*state));
}
// Retrieve the GWP-ASan metadata pool from `metadata_addr` inside the process
// at `process_memory`. The number of metadata slots is retrieved from the
// allocator state provided. This function returns a heap-allocated copy of the
// metadata pool whose ownership should be managed by the caller. Returns
// nullptr on failure.
static const gwp_asan::AllocationMetadata* retrieve_gwp_asan_metadata(
unwindstack::Memory* process_memory, const gwp_asan::AllocatorState& state,
uintptr_t metadata_addr) {
if (state.MaxSimultaneousAllocations > 1024) {
ALOGE(
"Error when retrieving GWP-ASan metadata, MSA from state (%zu) "
"exceeds maximum allowed (1024).",
state.MaxSimultaneousAllocations);
return nullptr;
}
gwp_asan::AllocationMetadata* meta =
new gwp_asan::AllocationMetadata[state.MaxSimultaneousAllocations];
if (!process_memory->ReadFully(metadata_addr, meta,
sizeof(*meta) * state.MaxSimultaneousAllocations)) {
ALOGE(
"Error when retrieving GWP-ASan metadata, could not retrieve %zu "
"pieces of metadata.",
state.MaxSimultaneousAllocations);
delete[] meta;
meta = nullptr;
}
return meta;
}
GwpAsanCrashData::GwpAsanCrashData(unwindstack::Memory* process_memory,
const ProcessInfo& process_info, const ThreadInfo& thread_info) {
if (!process_memory || !process_info.gwp_asan_metadata || !process_info.gwp_asan_state) return;
// Extract the GWP-ASan regions from the dead process.
if (!retrieve_gwp_asan_state(process_memory, process_info.gwp_asan_state, &state_)) return;
metadata_.reset(retrieve_gwp_asan_metadata(process_memory, state_, process_info.gwp_asan_metadata));
if (!metadata_.get()) return;
// Get the external crash address from the thread info.
crash_address_ = 0u;
if (process_info.has_fault_address) {
crash_address_ = process_info.untagged_fault_address;
}
// Ensure the error belongs to GWP-ASan.
if (!__gwp_asan_error_is_mine(&state_, crash_address_)) return;
is_gwp_asan_responsible_ = true;
thread_id_ = thread_info.tid;
// Grab the internal error address, if it exists.
uintptr_t internal_crash_address = __gwp_asan_get_internal_crash_address(&state_);
if (internal_crash_address) {
crash_address_ = internal_crash_address;
}
// Get other information from the internal state.
error_ = __gwp_asan_diagnose_error(&state_, metadata_.get(), crash_address_);
error_string_ = gwp_asan::ErrorToString(error_);
responsible_allocation_ = __gwp_asan_get_metadata(&state_, metadata_.get(), crash_address_);
}
bool GwpAsanCrashData::CrashIsMine() const {
return is_gwp_asan_responsible_;
}
constexpr size_t kMaxTraceLength = gwp_asan::AllocationMetadata::kMaxTraceLengthToCollect;
void GwpAsanCrashData::AddCauseProtos(Tombstone* tombstone, unwindstack::Unwinder* unwinder) const {
if (!CrashIsMine()) {
ALOGE("Internal Error: AddCauseProtos() on a non-GWP-ASan crash.");
return;
}
Cause* cause = tombstone->add_causes();
MemoryError* memory_error = cause->mutable_memory_error();
HeapObject* heap_object = memory_error->mutable_heap();
memory_error->set_tool(MemoryError_Tool_GWP_ASAN);
switch (error_) {
case gwp_asan::Error::USE_AFTER_FREE:
memory_error->set_type(MemoryError_Type_USE_AFTER_FREE);
break;
case gwp_asan::Error::DOUBLE_FREE:
memory_error->set_type(MemoryError_Type_DOUBLE_FREE);
break;
case gwp_asan::Error::INVALID_FREE:
memory_error->set_type(MemoryError_Type_INVALID_FREE);
break;
case gwp_asan::Error::BUFFER_OVERFLOW:
memory_error->set_type(MemoryError_Type_BUFFER_OVERFLOW);
break;
case gwp_asan::Error::BUFFER_UNDERFLOW:
memory_error->set_type(MemoryError_Type_BUFFER_UNDERFLOW);
break;
default:
memory_error->set_type(MemoryError_Type_UNKNOWN);
break;
}
heap_object->set_address(__gwp_asan_get_allocation_address(responsible_allocation_));
heap_object->set_size(__gwp_asan_get_allocation_size(responsible_allocation_));
unwinder->SetDisplayBuildID(true);
std::unique_ptr<uintptr_t[]> frames(new uintptr_t[kMaxTraceLength]);
heap_object->set_allocation_tid(__gwp_asan_get_allocation_thread_id(responsible_allocation_));
size_t num_frames =
__gwp_asan_get_allocation_trace(responsible_allocation_, frames.get(), kMaxTraceLength);
for (size_t i = 0; i != num_frames; ++i) {
unwindstack::FrameData frame_data = unwinder->BuildFrameFromPcOnly(frames[i]);
BacktraceFrame* f = heap_object->add_allocation_backtrace();
fill_in_backtrace_frame(f, frame_data);
}
heap_object->set_deallocation_tid(__gwp_asan_get_deallocation_thread_id(responsible_allocation_));
num_frames =
__gwp_asan_get_deallocation_trace(responsible_allocation_, frames.get(), kMaxTraceLength);
for (size_t i = 0; i != num_frames; ++i) {
unwindstack::FrameData frame_data = unwinder->BuildFrameFromPcOnly(frames[i]);
BacktraceFrame* f = heap_object->add_deallocation_backtrace();
fill_in_backtrace_frame(f, frame_data);
}
set_human_readable_cause(cause, crash_address_);
}
void GwpAsanCrashData::DumpCause(log_t* log) const {
if (!CrashIsMine()) {
ALOGE("Internal Error: DumpCause() on a non-GWP-ASan crash.");
return;
}
if (error_ == gwp_asan::Error::UNKNOWN) {
_LOG(log, logtype::HEADER, "Cause: [GWP-ASan]: Unknown error occurred at 0x%" PRIxPTR ".\n",
crash_address_);
return;
}
if (!responsible_allocation_) {
_LOG(log, logtype::HEADER, "Cause: [GWP-ASan]: %s at 0x%" PRIxPTR ".\n", error_string_,
crash_address_);
return;
}
uintptr_t alloc_address = __gwp_asan_get_allocation_address(responsible_allocation_);
size_t alloc_size = __gwp_asan_get_allocation_size(responsible_allocation_);
uintptr_t diff;
const char* location_str;
if (crash_address_ < alloc_address) {
// Buffer Underflow, 6 bytes left of a 41-byte allocation at 0xdeadbeef.
location_str = "left of";
diff = alloc_address - crash_address_;
} else if (crash_address_ - alloc_address < alloc_size) {
// Use After Free, 40 bytes into a 41-byte allocation at 0xdeadbeef.
location_str = "into";
diff = crash_address_ - alloc_address;
} else {
// Buffer Overflow, 6 bytes right of a 41-byte allocation at 0xdeadbeef, or
// Invalid Free, 47 bytes right of a 41-byte allocation at 0xdeadbeef.
location_str = "right of";
diff = crash_address_ - alloc_address;
if (error_ == gwp_asan::Error::BUFFER_OVERFLOW) {
diff -= alloc_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,
"Cause: [GWP-ASan]: %s, %" PRIuPTR " byte%s %s a %zu-byte allocation at 0x%" PRIxPTR "\n",
error_string_, diff, byte_suffix, location_str, alloc_size, alloc_address);
}
bool GwpAsanCrashData::HasDeallocationTrace() const {
assert(CrashIsMine() && "HasDeallocationTrace(): Crash is not mine!");
if (!responsible_allocation_ || !__gwp_asan_is_deallocated(responsible_allocation_)) {
return false;
}
return true;
}
void GwpAsanCrashData::DumpDeallocationTrace(log_t* log, unwindstack::Unwinder* unwinder) const {
assert(HasDeallocationTrace() && "DumpDeallocationTrace(): No dealloc trace!");
uint64_t thread_id = __gwp_asan_get_deallocation_thread_id(responsible_allocation_);
std::unique_ptr<uintptr_t[]> frames(new uintptr_t[kMaxTraceLength]);
size_t num_frames =
__gwp_asan_get_deallocation_trace(responsible_allocation_, frames.get(), kMaxTraceLength);
if (thread_id == gwp_asan::kInvalidThreadID) {
_LOG(log, logtype::BACKTRACE, "\ndeallocated by thread <unknown>:\n");
} else {
_LOG(log, logtype::BACKTRACE, "\ndeallocated by thread %" PRIu64 ":\n", thread_id);
}
unwinder->SetDisplayBuildID(true);
for (size_t i = 0; i < num_frames; ++i) {
unwindstack::FrameData frame_data = unwinder->BuildFrameFromPcOnly(frames[i]);
frame_data.num = i;
_LOG(log, logtype::BACKTRACE, " %s\n", unwinder->FormatFrame(frame_data).c_str());
}
}
bool GwpAsanCrashData::HasAllocationTrace() const {
assert(CrashIsMine() && "HasAllocationTrace(): Crash is not mine!");
return responsible_allocation_ != nullptr;
}
void GwpAsanCrashData::DumpAllocationTrace(log_t* log, unwindstack::Unwinder* unwinder) const {
assert(HasAllocationTrace() && "DumpAllocationTrace(): No dealloc trace!");
uint64_t thread_id = __gwp_asan_get_allocation_thread_id(responsible_allocation_);
std::unique_ptr<uintptr_t[]> frames(new uintptr_t[kMaxTraceLength]);
size_t num_frames =
__gwp_asan_get_allocation_trace(responsible_allocation_, frames.get(), kMaxTraceLength);
if (thread_id == gwp_asan::kInvalidThreadID) {
_LOG(log, logtype::BACKTRACE, "\nallocated by thread <unknown>:\n");
} else {
_LOG(log, logtype::BACKTRACE, "\nallocated by thread %" PRIu64 ":\n", thread_id);
}
unwinder->SetDisplayBuildID(true);
for (size_t i = 0; i < num_frames; ++i) {
unwindstack::FrameData frame_data = unwinder->BuildFrameFromPcOnly(frames[i]);
frame_data.num = i;
_LOG(log, logtype::BACKTRACE, " %s\n", unwinder->FormatFrame(frame_data).c_str());
}
}