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libsystem_malloc.dylib free list parser
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import lldb, struct, shutil | |
COLOR_YELLOW = '\x1b[33m' | |
COLOR_GREEN = '\x1b[32m' | |
COLOR_BLUE = '\x1b[34m' | |
COLOR_RED = '\x1b[31m' | |
COLOR_GREY = '\x1b[90m' | |
COLOR_WHITE = '\x1b[0m' | |
COLOR_MAGENTA = '\x1b[35m' | |
COLOR_CYAN = '\x1b[36m' | |
debugger = None | |
def format_hex(n, pad = 0): | |
return '0x' + hex(n)[2:].rjust(pad, '0') | |
def read(addr, size): | |
error = lldb.SBError() | |
mem = process.ReadMemory(addr, size, error) | |
if not error.Success(): | |
return None | |
return mem | |
def runCmd(cmd): | |
ci = debugger.GetCommandInterpreter() | |
res = lldb.SBCommandReturnObject() | |
ci.HandleCommand(cmd, res) | |
if not res.Succeeded(): | |
return None | |
return res.GetOutput() | |
def getImageBase(imageName): | |
return int(runCmd(f'image list {imageName}').split('0x')[1].split()[0], 16) | |
def exprToUint64(expr): | |
return int(runCmd(f'p/x (uint64_t)({expr})').split('=')[1], 16) | |
def exprToStr(expr): | |
return runCmd(expr).strip() | |
def readUint64(addr): | |
return struct.unpack('Q', read(addr, 8))[0] | |
def readUint32(addr): | |
return struct.unpack('I', read(addr, 4))[0] | |
def readUint16(addr): | |
return struct.unpack('H', read(addr, 2))[0] | |
def readUint8(addr): | |
return struct.unpack('B', read(addr, 1))[0] | |
def set_global(dbg): | |
global debugger, target, process | |
debugger = dbg | |
target = debugger.GetSelectedTarget() | |
process = target.GetProcess() | |
def print_banner(s): | |
columns = shutil.get_terminal_size().columns | |
mul = (columns - len(s) - 4) // 2 | |
print('-'*mul + f'[ {s} ]' + '-'*mul) | |
def print_node(name, address, level = 0): | |
if address == 0: | |
return | |
if 'TINY' in name: | |
prev = readUint64(address) | |
next = readUint64(address + 8) | |
msize = readUint16(address + 0x10) | |
print(f' ({str(level).rjust(3)}) [ {COLOR_RED}{hex(address)}{COLOR_WHITE} prev: {COLOR_BLUE}{hex(prev)}{COLOR_WHITE} next: {COLOR_BLUE}{hex(next)}{COLOR_WHITE} msize: {COLOR_BLUE}{hex(msize)}{COLOR_WHITE}0 ]') | |
print_node(name, next, level + 1) | |
elif 'SMALL' in name: | |
prev = readUint64(address) | |
prev_checksum = readUint64(address + 0x8) & 0xff | |
next = readUint64(address + 0x10) | |
next_checksum = readUint64(address + 0x18) & 0xff | |
print(f' ({str(level).rjust(3)}) [ {COLOR_RED}{hex(address)}{COLOR_WHITE} prev: {COLOR_BLUE}{hex(prev)}{COLOR_WHITE} prev_checksum: {COLOR_BLUE}{hex(prev_checksum)}{COLOR_WHITE} next: {COLOR_BLUE}{hex(next)}{COLOR_WHITE} next_checksum: {COLOR_BLUE}{hex(next_checksum)}{COLOR_WHITE} ]') | |
print_node(name, next, level + 1) | |
elif 'MEDIUM' in name: | |
prev = readUint64(address) | |
next = readUint64(address + 8) | |
print(f' ({str(level).rjust(3)}) [ {COLOR_RED}{hex(address)}{COLOR_WHITE} prev: {COLOR_BLUE}{hex(prev)}{COLOR_WHITE} next: {COLOR_BLUE}{hex(next)}{COLOR_WHITE} ]') | |
print_node(name, next, level + 1) | |
else: | |
print('THIS SHOULDN\'T BE PRINTED') | |
return | |
def print_rack(name, rack, unit): | |
num_magazines = readUint32(rack + 0x260) | |
megazines = readUint64(rack + 0x270) | |
print(f'( {name}->num_magazines: {COLOR_BLUE}{hex(num_magazines)}{COLOR_WHITE} )') | |
print(f'( {name}->megazines: {COLOR_BLUE}{hex(megazines)}{COLOR_WHITE} )') | |
for mag_index in range(num_magazines): | |
megazine = megazines + 0xa00 * mag_index | |
print(f'( {name}->megazines[{mag_index}] @ {COLOR_RED}{hex(megazine)}{COLOR_WHITE} ', end = '') | |
magazine_lock = readUint64(megazine) | |
mag_last_free = readUint64(megazine + 8) | |
mag_last_free_msize = readUint64(megazine + 0x10) | |
mag_last_free_rgn = readUint64(megazine + 0x18) | |
mag_bytes_free_at_end = readUint64(megazine + 0x850) | |
mag_last_region = readUint64(megazine + 0x860) | |
firstNode = readUint64(megazine + 0x880) | |
lastNode = readUint64(megazine + 0x880) | |
print(f'magazine_lock: {COLOR_BLUE}{hex(magazine_lock)}{COLOR_WHITE} ', end = '') | |
print(f'mag_last_free: {COLOR_BLUE}{hex(mag_last_free)}{COLOR_WHITE} ', end = '') | |
if mag_last_free_msize and mag_last_free: | |
print(f'mag_last_free_msize: {COLOR_BLUE}{hex(mag_last_free_msize)}{COLOR_WHITE} ({COLOR_YELLOW}{hex(mag_last_free_msize * unit)}{COLOR_WHITE}) ', end = '') | |
else: | |
print(f'mag_last_free_msize: {COLOR_BLUE}{hex(mag_last_free_msize)}{COLOR_WHITE} ', end = '') | |
print(f'mag_last_free_rgn: {COLOR_BLUE}{hex(mag_last_free_rgn)}{COLOR_WHITE} ', end = '') | |
print(f'mag_bytes_free_at_end: {COLOR_BLUE}{hex(mag_bytes_free_at_end)}{COLOR_WHITE} ', end = '') | |
print(f'mag_last_region: {COLOR_BLUE}{hex(mag_last_region)}{COLOR_WHITE} ', end = ')\n') | |
for k in range(64): | |
addr = megazine + 0x20 + k * 8 | |
val = readUint64(addr) | |
if val != 0: | |
print(f' [>] mag_free_list[{k}] ({COLOR_BLUE}{hex((k + 1) * unit)}{COLOR_WHITE}) -> {COLOR_RED}{hex(val)}{COLOR_WHITE}') | |
print_node(name, val) | |
def findSymbol(name): | |
return target.FindSymbols(name)[0].symbol.addr.GetLoadAddress(target) | |
def readString(address): | |
content = b'' | |
for i in range(100): | |
content += read(address, 0x10) | |
address += 0x10 | |
index = content.find(b'\0') | |
if index != -1: | |
return content[:index].decode() | |
return '' | |
def parse_malloc(debugger, command, result, internal_dict): | |
set_global(debugger) | |
malloc_zones = readUint64(findSymbol('malloc_zones')) | |
print(f'[*] malloc_zones: {COLOR_BLUE}{hex(malloc_zones)}{COLOR_WHITE}') | |
for k in range(0x10): | |
zone = readUint64(malloc_zones + k * 8) | |
if not zone: | |
break | |
zone_name = readString(readUint64(zone + 0x48)) | |
print_banner(f'{COLOR_RED}{zone_name}{COLOR_WHITE} @ {COLOR_BLUE}{hex(zone)}{COLOR_WHITE}') | |
is_medium_engaged = readUint8(zone + 0x4fd8) | |
tiny_rack = zone + 0x4080 | |
small_rack = zone + 0x4380 | |
medium_rack = zone + 0x4680 | |
print_rack(f'\x1b[44mTINY{COLOR_WHITE}', tiny_rack, 0x10) | |
print_rack(f'\x1b[43mSMALL{COLOR_WHITE}', small_rack, 0x200) | |
if is_medium_engaged: | |
print_rack(f'\x1b[45mMEDIUM{COLOR_WHITE}', medium_rack, 0x8000) | |
def __lldb_init_module(debugger, internal_dict): | |
debugger.HandleCommand('command script add -o -f {}.parse_malloc parse_malloc'.format(__name__)) |
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