platform_bionic/libc/malloc_debug/FreeTrackData.cpp
Christopher Ferris 7993b80f89 Add better free tracking.
Included in this change:

- Change the tag when a pointer is freed so it's easy to detect if
  an already freed pointer is being used.
- Move the free backtrace out of the header. This backtrace is only
  used under only some circumstances, so no need to allocate space
  in all headers for it.
- Add new option free_track_backtrace_num_frames to specify how many
  frames to record when the free occurs. This removes the dependency
  on the backtrace option to get backtraces.

Bug: 26739265
Change-Id: I76f5209507dcf46af67ada162a7cb2bf282116f2
2016-01-29 15:19:22 -08:00

135 lines
4.9 KiB
C++

/*
* Copyright (C) 2015 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <stdint.h>
#include "backtrace.h"
#include "Config.h"
#include "DebugData.h"
#include "debug_disable.h"
#include "debug_log.h"
#include "FreeTrackData.h"
#include "malloc_debug.h"
FreeTrackData::FreeTrackData(const Config& config)
: backtrace_num_frames_(config.free_track_backtrace_num_frames) {
cmp_mem_.resize(4096);
memset(cmp_mem_.data(), config.fill_free_value, cmp_mem_.size());
}
void FreeTrackData::LogFreeError(DebugData& debug, const Header* header,
const uint8_t* pointer) {
ScopedDisableDebugCalls disable;
error_log(LOG_DIVIDER);
error_log("+++ ALLOCATION %p USED AFTER FREE", pointer);
uint8_t fill_free_value = debug.config().fill_free_value;
for (size_t i = 0; i < header->usable_size; i++) {
if (pointer[i] != fill_free_value) {
error_log(" pointer[%zu] = 0x%02x (expected 0x%02x)", i, pointer[i], fill_free_value);
}
}
auto back_iter = backtraces_.find(header);
if (back_iter != backtraces_.end()) {
const BacktraceHeader* back_header = back_iter->second;
error_log("Backtrace at time of free:");
backtrace_log(&back_header->frames[0], back_header->num_frames);
}
error_log(LOG_DIVIDER);
}
void FreeTrackData::VerifyAndFree(DebugData& debug, const Header* header,
const void* pointer) {
ScopedDisableDebugCalls disable;
const uint8_t* memory = reinterpret_cast<const uint8_t*>(pointer);
size_t bytes = header->usable_size;
bytes = (bytes < debug.config().fill_on_free_bytes) ? bytes : debug.config().fill_on_free_bytes;
while (bytes > 0) {
size_t bytes_to_cmp = (bytes < cmp_mem_.size()) ? bytes : cmp_mem_.size();
if (memcmp(memory, cmp_mem_.data(), bytes_to_cmp) != 0) {
LogFreeError(debug, header, reinterpret_cast<const uint8_t*>(pointer));
break;
}
bytes -= bytes_to_cmp;
memory = &memory[bytes_to_cmp];
}
auto back_iter = backtraces_.find(header);
if (back_iter != backtraces_.end()) {
g_dispatch->free(reinterpret_cast<void*>(back_iter->second));
backtraces_.erase(header);
}
g_dispatch->free(header->orig_pointer);
}
void FreeTrackData::Add(DebugData& debug, const Header* header) {
// Make sure the stl calls below don't call the debug_XXX functions.
ScopedDisableDebugCalls disable;
pthread_mutex_lock(&mutex_);
if (list_.size() == debug.config().free_track_allocations) {
const Header* old_header = list_.back();
VerifyAndFree(debug, old_header, debug.GetPointer(old_header));
list_.pop_back();
}
// Only log the free backtrace if we are using the free track feature.
if (backtrace_num_frames_ > 0) {
BacktraceHeader* back_header = reinterpret_cast<BacktraceHeader*>(
g_dispatch->malloc(sizeof(BacktraceHeader) + backtrace_num_frames_ * sizeof(uintptr_t)));
if (back_header) {
back_header->num_frames = backtrace_get(&back_header->frames[0], backtrace_num_frames_);
backtraces_[header] = back_header;
}
}
list_.push_front(header);
pthread_mutex_unlock(&mutex_);
}
void FreeTrackData::VerifyAll(DebugData& debug) {
// Make sure the stl calls below don't call the debug_XXX functions.
ScopedDisableDebugCalls disable;
for (const auto& header : list_) {
VerifyAndFree(debug, header, debug.GetPointer(header));
}
list_.clear();
}
void FreeTrackData::LogBacktrace(const Header* header) {
ScopedDisableDebugCalls disable;
auto back_iter = backtraces_.find(header);
if (back_iter == backtraces_.end()) {
return;
}
error_log("Backtrace of original free:");
backtrace_log(&back_iter->second->frames[0], back_iter->second->num_frames);
}