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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. 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 HOLDER 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 "MallocTracer.h"
#include "Emulator.h"
#include "MmapRegion.h"
#include <AK/LogStream.h>
//#define REACHABLE_DEBUG
namespace UserspaceEmulator {
static pid_t s_pid = getpid();
MallocTracer::MallocTracer()
{
}
void MallocTracer::target_did_malloc(Badge<SoftCPU>, FlatPtr address, size_t size)
{
if (auto* existing_mallocation = find_mallocation(address)) {
ASSERT(existing_mallocation->freed);
existing_mallocation->size = size;
existing_mallocation->freed = false;
return;
}
m_mallocations.append({ address, size, false, Emulator::the().raw_backtrace(), Vector<FlatPtr>() });
}
void MallocTracer::target_did_free(Badge<SoftCPU>, FlatPtr address)
{
if (!address)
return;
for (auto& mallocation : m_mallocations) {
if (mallocation.address == address) {
if (mallocation.freed) {
dbgprintf("\n");
dbgprintf("==%d== \033[31;1mDouble free()\033[0m, %p\n", s_pid, address);
dbgprintf("==%d== Address %p has already been passed to free()\n", s_pid, address);
Emulator::the().dump_backtrace();
} else {
mallocation.freed = true;
mallocation.free_backtrace = Emulator::the().raw_backtrace();
}
return;
}
}
dbgprintf("\n");
dbgprintf("==%d== \033[31;1mInvalid free()\033[0m, %p\n", s_pid, address);
dbgprintf("==%d== Address %p has never been returned by malloc()\n", s_pid, address);
Emulator::the().dump_backtrace();
}
MallocTracer::Mallocation* MallocTracer::find_mallocation(FlatPtr address)
{
for (auto& mallocation : m_mallocations) {
if (mallocation.contains(address))
return &mallocation;
}
return nullptr;
}
void MallocTracer::audit_read(FlatPtr address, size_t size)
{
if (!m_auditing_enabled)
return;
if (Emulator::the().is_in_malloc_or_free())
return;
auto* mallocation = find_mallocation(address);
if (!mallocation)
return;
size_t offset_into_mallocation = address - mallocation->address;
if (mallocation->freed) {
dbgprintf("\n");
dbgprintf("==%d== \033[31;1mUse-after-free\033[0m, invalid %zu-byte read at address %p\n", s_pid, size, address);
Emulator::the().dump_backtrace();
dbgprintf("==%d== Address is %zu bytes into block of size %zu, allocated at:\n", s_pid, offset_into_mallocation, mallocation->size);
Emulator::the().dump_backtrace(mallocation->malloc_backtrace);
dbgprintf("==%d== Later freed at:\n", s_pid, offset_into_mallocation, mallocation->size);
Emulator::the().dump_backtrace(mallocation->free_backtrace);
return;
}
}
void MallocTracer::audit_write(FlatPtr address, size_t size)
{
if (!m_auditing_enabled)
return;
if (Emulator::the().is_in_malloc_or_free())
return;
auto* mallocation = find_mallocation(address);
if (!mallocation)
return;
size_t offset_into_mallocation = address - mallocation->address;
if (mallocation->freed) {
dbgprintf("\n");
dbgprintf("==%d== \033[31;1mUse-after-free\033[0m, invalid %zu-byte write at address %p\n", s_pid, size, address);
Emulator::the().dump_backtrace();
dbgprintf("==%d== Address is %zu bytes into block of size %zu, allocated at:\n", s_pid, offset_into_mallocation, mallocation->size);
Emulator::the().dump_backtrace(mallocation->malloc_backtrace);
dbgprintf("==%d== Later freed at:\n", s_pid, offset_into_mallocation, mallocation->size);
Emulator::the().dump_backtrace(mallocation->free_backtrace);
return;
}
}
bool MallocTracer::is_reachable(const Mallocation& mallocation) const
{
ASSERT(!mallocation.freed);
// 1. Search in active (non-freed) mallocations for pointers to this mallocation
for (auto& other_mallocation : m_mallocations) {
if (&mallocation == &other_mallocation)
continue;
size_t pointers_in_mallocation = other_mallocation.size / sizeof(u32);
for (size_t i = 0; i < pointers_in_mallocation; ++i) {
auto value = Emulator::the().mmu().read32({ 0x20, other_mallocation.address + i * sizeof(u32) });
if (value == mallocation.address) {
#ifdef REACHABLE_DEBUG
dbgprintf("mallocation %p is reachable from other mallocation %p\n", mallocation.address, other_mallocation.address);
#endif
return true;
}
}
}
bool reachable = false;
// 2. Search in other memory regions for pointers to this mallocation
Emulator::the().mmu().for_each_region([&](auto& region) {
// Skip the stack
if (region.is_stack())
return IterationDecision::Continue;
if (region.is_text())
return IterationDecision::Continue;
// Skip malloc blocks
if (region.is_mmap() && static_cast<const MmapRegion&>(region).is_malloc_block())
return IterationDecision::Continue;
size_t pointers_in_region = region.size() / sizeof(u32);
for (size_t i = 0; i < pointers_in_region; ++i) {
auto value = region.read32(i * sizeof(u32));
if (value == mallocation.address) {
#ifdef REACHABLE_DEBUG
dbgprintf("mallocation %p is reachable from region %p-%p\n", mallocation.address, region.base(), region.end() - 1);
#endif
reachable = true;
return IterationDecision::Break;
}
}
return IterationDecision::Continue;
});
return reachable;
}
void MallocTracer::dump_leak_report()
{
TemporaryChange change(m_auditing_enabled, false);
size_t bytes_leaked = 0;
size_t leaks_found = 0;
for (auto& mallocation : m_mallocations) {
if (mallocation.freed)
continue;
if (is_reachable(mallocation))
continue;
++leaks_found;
bytes_leaked += mallocation.size;
dbgprintf("\n");
dbgprintf("==%d== \033[31;1mLeak\033[0m, %zu-byte allocation at address %p\n", s_pid, mallocation.size, mallocation.address);
Emulator::the().dump_backtrace(mallocation.malloc_backtrace);
}
dbgprintf("\n");
if (!leaks_found)
dbgprintf("==%d== \033[32;1mNo leaks found!\033[0m\n", s_pid);
else
dbgprintf("==%d== \033[31;1m%zu leak(s) found: %zu byte(s) leaked\033[0m\n", s_pid, leaks_found, bytes_leaked);
}
}
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