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72ca45e300
When loading dynamic objects, the emulator loads the interpreter, generates an auxiliary vector and starts executing the loader. Additionally, this commits also makes the MallocTracer and backtrace symbolication work for dynamically loaded programs.
379 lines
16 KiB
C++
379 lines
16 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "MallocTracer.h"
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#include "Emulator.h"
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#include "MmapRegion.h"
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#include <AK/LogStream.h>
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#include <AK/TemporaryChange.h>
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#include <mallocdefs.h>
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#include <string.h>
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//#define REACHABLE_DEBUG
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namespace UserspaceEmulator {
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MallocTracer::MallocTracer(Emulator& emulator)
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: m_emulator(emulator)
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{
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}
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template<typename Callback>
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inline void MallocTracer::for_each_mallocation(Callback callback) const
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{
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m_emulator.mmu().for_each_region([&](auto& region) {
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if (region.is_mmap() && static_cast<const MmapRegion&>(region).is_malloc_block()) {
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auto* malloc_data = static_cast<MmapRegion&>(region).malloc_metadata();
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for (auto& mallocation : malloc_data->mallocations) {
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if (mallocation.used && callback(mallocation) == IterationDecision::Break)
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return IterationDecision::Break;
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}
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}
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return IterationDecision::Continue;
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});
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}
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void MallocTracer::target_did_malloc(Badge<SoftCPU>, FlatPtr address, size_t size)
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{
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if (m_emulator.is_in_loader_code())
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return;
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auto* region = m_emulator.mmu().find_region({ 0x20, address });
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ASSERT(region);
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ASSERT(region->is_mmap());
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auto& mmap_region = static_cast<MmapRegion&>(*region);
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// Mark the containing mmap region as a malloc block!
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mmap_region.set_malloc(true);
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auto* shadow_bits = mmap_region.shadow_data() + address - mmap_region.base();
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memset(shadow_bits, 0, size);
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if (auto* existing_mallocation = find_mallocation(address)) {
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ASSERT(existing_mallocation->freed);
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existing_mallocation->size = size;
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existing_mallocation->freed = false;
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existing_mallocation->malloc_backtrace = m_emulator.raw_backtrace();
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existing_mallocation->free_backtrace.clear();
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return;
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}
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MallocRegionMetadata* malloc_data = static_cast<MmapRegion&>(*region).malloc_metadata();
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if (!malloc_data) {
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auto new_malloc_data = make<MallocRegionMetadata>();
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malloc_data = new_malloc_data.ptr();
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static_cast<MmapRegion&>(*region).set_malloc_metadata({}, move(new_malloc_data));
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malloc_data->address = region->base();
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malloc_data->chunk_size = mmap_region.read32(offsetof(CommonHeader, m_size)).value();
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bool is_chunked_block = malloc_data->chunk_size <= size_classes[num_size_classes - 1];
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if (is_chunked_block)
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malloc_data->mallocations.resize((ChunkedBlock::block_size - sizeof(ChunkedBlock)) / malloc_data->chunk_size);
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else
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malloc_data->mallocations.resize(1);
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dbgln("Tracking malloc block @ {:p} with chunk_size={}, chunk_count={}", malloc_data->address, malloc_data->chunk_size, malloc_data->mallocations.size());
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}
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malloc_data->mallocation_for_address(address) = { address, size, true, false, m_emulator.raw_backtrace(), Vector<FlatPtr>() };
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}
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ALWAYS_INLINE Mallocation& MallocRegionMetadata::mallocation_for_address(FlatPtr address) const
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{
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return const_cast<Mallocation&>(this->mallocations[chunk_index_for_address(address)]);
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}
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ALWAYS_INLINE size_t MallocRegionMetadata::chunk_index_for_address(FlatPtr address) const
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{
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bool is_chunked_block = chunk_size <= size_classes[num_size_classes - 1];
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if (!is_chunked_block) {
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// This is a BigAllocationBlock
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return 0;
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}
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auto chunk_offset = address - (this->address + sizeof(ChunkedBlock));
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ASSERT(this->chunk_size);
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return chunk_offset / this->chunk_size;
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}
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void MallocTracer::target_did_free(Badge<SoftCPU>, FlatPtr address)
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{
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if (!address)
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return;
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if (m_emulator.is_in_loader_code())
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return;
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if (auto* mallocation = find_mallocation(address)) {
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if (mallocation->freed) {
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reportln("\n=={}== \033[31;1mDouble free()\033[0m, {:p}", getpid(), address);
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reportln("=={}== Address {} has already been passed to free()", getpid(), address);
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m_emulator.dump_backtrace();
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} else {
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mallocation->freed = true;
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mallocation->free_backtrace = m_emulator.raw_backtrace();
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}
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return;
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}
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reportln("\n=={}== \033[31;1mInvalid free()\033[0m, {:p}", getpid(), address);
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reportln("=={}== Address {} has never been returned by malloc()", getpid(), address);
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m_emulator.dump_backtrace();
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}
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void MallocTracer::target_did_realloc(Badge<SoftCPU>, FlatPtr address, size_t size)
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{
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if (m_emulator.is_in_loader_code())
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return;
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auto* region = m_emulator.mmu().find_region({ 0x20, address });
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ASSERT(region);
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ASSERT(region->is_mmap());
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auto& mmap_region = static_cast<MmapRegion&>(*region);
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ASSERT(mmap_region.is_malloc_block());
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auto* existing_mallocation = find_mallocation(address);
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ASSERT(existing_mallocation);
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ASSERT(!existing_mallocation->freed);
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size_t old_size = existing_mallocation->size;
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auto* shadow_bits = mmap_region.shadow_data() + address - mmap_region.base();
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if (size > old_size) {
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memset(shadow_bits + old_size, 1, size - old_size);
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} else {
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memset(shadow_bits + size, 1, old_size - size);
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}
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existing_mallocation->size = size;
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// FIXME: Should we track malloc/realloc backtrace separately perhaps?
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existing_mallocation->malloc_backtrace = m_emulator.raw_backtrace();
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}
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Mallocation* MallocTracer::find_mallocation(FlatPtr address)
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{
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auto* region = m_emulator.mmu().find_region({ 0x23, address });
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if (!region)
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return nullptr;
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return find_mallocation(*region, address);
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}
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Mallocation* MallocTracer::find_mallocation_before(FlatPtr address)
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{
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Mallocation* found_mallocation = nullptr;
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for_each_mallocation([&](auto& mallocation) {
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if (mallocation.address >= address)
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return IterationDecision::Continue;
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if (!found_mallocation || (mallocation.address > found_mallocation->address))
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found_mallocation = const_cast<Mallocation*>(&mallocation);
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return IterationDecision::Continue;
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});
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return found_mallocation;
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}
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Mallocation* MallocTracer::find_mallocation_after(FlatPtr address)
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{
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Mallocation* found_mallocation = nullptr;
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for_each_mallocation([&](auto& mallocation) {
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if (mallocation.address <= address)
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return IterationDecision::Continue;
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if (!found_mallocation || (mallocation.address < found_mallocation->address))
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found_mallocation = const_cast<Mallocation*>(&mallocation);
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return IterationDecision::Continue;
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});
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return found_mallocation;
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}
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void MallocTracer::audit_read(const Region& region, FlatPtr address, size_t size)
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{
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if (!m_auditing_enabled)
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return;
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if (m_emulator.is_in_malloc_or_free()) {
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return;
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}
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if (m_emulator.is_in_loader_code()) {
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return;
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}
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auto* mallocation = find_mallocation(region, address);
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if (!mallocation) {
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reportln("\n=={}== \033[31;1mHeap buffer overflow\033[0m, invalid {}-byte read at address {:p}", getpid(), size, address);
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m_emulator.dump_backtrace();
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auto* mallocation_before = find_mallocation_before(address);
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auto* mallocation_after = find_mallocation_after(address);
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size_t distance_to_mallocation_before = mallocation_before ? (address - mallocation_before->address - mallocation_before->size) : 0;
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size_t distance_to_mallocation_after = mallocation_after ? (mallocation_after->address - address) : 0;
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if (mallocation_before && (!mallocation_after || distance_to_mallocation_before < distance_to_mallocation_after)) {
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reportln("=={}== Address is {} byte(s) after block of size {}, identity {:p}, allocated at:", getpid(), distance_to_mallocation_before, mallocation_before->size, mallocation_before->address);
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m_emulator.dump_backtrace(mallocation_before->malloc_backtrace);
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return;
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}
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if (mallocation_after && (!mallocation_before || distance_to_mallocation_after < distance_to_mallocation_before)) {
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reportln("=={}== Address is {} byte(s) before block of size {}, identity {:p}, allocated at:", getpid(), distance_to_mallocation_after, mallocation_after->size, mallocation_after->address);
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m_emulator.dump_backtrace(mallocation_after->malloc_backtrace);
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}
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return;
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}
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size_t offset_into_mallocation = address - mallocation->address;
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if (mallocation->freed) {
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reportln("\n=={}== \033[31;1mUse-after-free\033[0m, invalid {}-byte read at address {:p}", getpid(), size, address);
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m_emulator.dump_backtrace();
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reportln("=={}== Address is {} byte(s) into block of size {}, allocated at:", getpid(), offset_into_mallocation, mallocation->size);
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m_emulator.dump_backtrace(mallocation->malloc_backtrace);
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reportln("=={}== Later freed at:", getpid());
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m_emulator.dump_backtrace(mallocation->free_backtrace);
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return;
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}
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}
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void MallocTracer::audit_write(const Region& region, FlatPtr address, size_t size)
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{
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if (!m_auditing_enabled)
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return;
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if (m_emulator.is_in_malloc_or_free())
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return;
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if (m_emulator.is_in_loader_code()) {
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return;
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}
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auto* mallocation = find_mallocation(region, address);
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if (!mallocation) {
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reportln("\n=={}== \033[31;1mHeap buffer overflow\033[0m, invalid {}-byte write at address {:p}", getpid(), size, address);
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m_emulator.dump_backtrace();
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auto* mallocation_before = find_mallocation_before(address);
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auto* mallocation_after = find_mallocation_after(address);
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size_t distance_to_mallocation_before = mallocation_before ? (address - mallocation_before->address - mallocation_before->size) : 0;
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size_t distance_to_mallocation_after = mallocation_after ? (mallocation_after->address - address) : 0;
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if (mallocation_before && (!mallocation_after || distance_to_mallocation_before < distance_to_mallocation_after)) {
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reportln("=={}== Address is {} byte(s) after block of size {}, identity {:p}, allocated at:", getpid(), distance_to_mallocation_before, mallocation_before->size, mallocation_before->address);
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m_emulator.dump_backtrace(mallocation_before->malloc_backtrace);
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return;
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}
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if (mallocation_after && (!mallocation_before || distance_to_mallocation_after < distance_to_mallocation_before)) {
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reportln("=={}== Address is {} byte(s) before block of size {}, identity {:p}, allocated at:", getpid(), distance_to_mallocation_after, mallocation_after->size, mallocation_after->address);
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m_emulator.dump_backtrace(mallocation_after->malloc_backtrace);
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}
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return;
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}
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size_t offset_into_mallocation = address - mallocation->address;
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if (mallocation->freed) {
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reportln("\n=={}== \033[31;1mUse-after-free\033[0m, invalid {}-byte write at address {:p}", getpid(), size, address);
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m_emulator.dump_backtrace();
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reportln("=={}== Address is {} byte(s) into block of size {}, allocated at:", getpid(), offset_into_mallocation, mallocation->size);
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m_emulator.dump_backtrace(mallocation->malloc_backtrace);
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reportln("=={}== Later freed at:", getpid());
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m_emulator.dump_backtrace(mallocation->free_backtrace);
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return;
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}
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}
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bool MallocTracer::is_reachable(const Mallocation& mallocation) const
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{
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ASSERT(!mallocation.freed);
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bool reachable = false;
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// 1. Search in active (non-freed) mallocations for pointers to this mallocation
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for_each_mallocation([&](auto& other_mallocation) {
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if (&mallocation == &other_mallocation)
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return IterationDecision::Continue;
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if (other_mallocation.freed)
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return IterationDecision::Continue;
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size_t pointers_in_mallocation = other_mallocation.size / sizeof(u32);
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for (size_t i = 0; i < pointers_in_mallocation; ++i) {
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auto value = m_emulator.mmu().read32({ 0x20, other_mallocation.address + i * sizeof(u32) });
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if (value.value() == mallocation.address && !value.is_uninitialized()) {
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#ifdef REACHABLE_DEBUG
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reportln("mallocation {:p} is reachable from other mallocation {:p}", mallocation.address, other_mallocation.address);
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#endif
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reachable = true;
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return IterationDecision::Break;
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}
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}
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return IterationDecision::Continue;
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});
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if (reachable)
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return true;
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// 2. Search in other memory regions for pointers to this mallocation
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m_emulator.mmu().for_each_region([&](auto& region) {
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// Skip the stack
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if (region.is_stack())
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return IterationDecision::Continue;
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if (region.is_text())
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return IterationDecision::Continue;
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if (!region.is_readable())
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return IterationDecision::Continue;
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// Skip malloc blocks
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if (region.is_mmap() && static_cast<const MmapRegion&>(region).is_malloc_block())
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return IterationDecision::Continue;
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size_t pointers_in_region = region.size() / sizeof(u32);
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for (size_t i = 0; i < pointers_in_region; ++i) {
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auto value = region.read32(i * sizeof(u32));
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if (value.value() == mallocation.address && !value.is_uninitialized()) {
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#ifdef REACHABLE_DEBUG
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reportln("mallocation {:p} is reachable from region {:p}-{:p}", mallocation.address, region.base(), region.end() - 1);
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#endif
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reachable = true;
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return IterationDecision::Break;
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}
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}
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return IterationDecision::Continue;
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});
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return reachable;
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}
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void MallocTracer::dump_leak_report()
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{
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TemporaryChange change(m_auditing_enabled, false);
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size_t bytes_leaked = 0;
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size_t leaks_found = 0;
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for_each_mallocation([&](auto& mallocation) {
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if (mallocation.freed)
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return IterationDecision::Continue;
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if (is_reachable(mallocation))
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return IterationDecision::Continue;
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++leaks_found;
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bytes_leaked += mallocation.size;
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reportln("\n=={}== \033[31;1mLeak\033[0m, {}-byte allocation at address {:p}", getpid(), mallocation.size, mallocation.address);
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m_emulator.dump_backtrace(mallocation.malloc_backtrace);
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return IterationDecision::Continue;
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});
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if (!leaks_found)
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reportln("\n=={}== \033[32;1mNo leaks found!\033[0m", getpid());
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else
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reportln("\n=={}== \033[31;1m{} leak(s) found: {} byte(s) leaked\033[0m", getpid(), leaks_found, bytes_leaked);
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}
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}
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