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Merge branch 'develop' into fix/symbolic_dos

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pull/1148/head
Bernhard Mueller 5 years ago committed by GitHub
parent be4a157cfd 1cce71c4ff
commit ad4cad6b1d
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  1. 102
      mythril/laser/ethereum/plugins/implementations/dependency_pruner.py

102
mythril/laser/ethereum/plugins/implementations/dependency_pruner.py
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@ -7,7 +7,6 @@ from mythril.laser.ethereum.transaction.transaction_models import (
ContractCreationTransaction,
)
from mythril.exceptions import UnsatError
from z3.z3types import Z3Exception
from mythril.analysis import solver
from typing import cast, List, Dict, Set
from copy import copy
@ -26,15 +25,15 @@ class DependencyAnnotation(StateAnnotation):
def __init__(self):
self.storage_loaded = [] # type: List
self.storage_written = {} # type: Dict[int, List]
self.has_call = False
self.path = [0] # type: List
self.blocks_seen = set() # type: Set[int]
def __copy__(self):
result = DependencyAnnotation()
result.storage_loaded = copy(self.storage_loaded)
result.storage_written = copy(self.storage_written)
result.path = copy(self.path)
result.has_call = self.has_call
result.blocks_seen = copy(self.blocks_seen)
return result
def get_storage_write_cache(self, iteration: int):
@ -44,15 +43,10 @@ class DependencyAnnotation(StateAnnotation):
return self.storage_written[iteration]
def extend_storage_write_cache(self, iteration: int, value: object):
try:
if iteration not in self.storage_written:
self.storage_written[iteration] = [value]
else:
if value not in self.storage_written[iteration]:
elif value not in self.storage_written[iteration]:
self.storage_written[iteration].append(value)
except Z3Exception as e:
# FIXME: This should not happen unless there's a bug in laser such as a BitVec512 being generated
log.debug("Error updating storage write cache: {}".format(e))
class WSDependencyAnnotation(StateAnnotation):
@ -140,41 +134,37 @@ class DependencyPruner(LaserPlugin):
def _reset(self):
self.iteration = 0
self.dependency_map = {} # type: Dict[int, List[object]]
self.protected_addresses = set() # type: Set[int]
self.sloads_on_path = {} # type: Dict[int, List[object]]
self.sstores_on_path = {} # type: Dict[int, List[object]]
self.storage_accessed_global = set() # type: Set
def update_dependency_map(self, path: List[int], target_location: object) -> None:
def update_sloads(self, path: List[int], target_location: object) -> None:
"""Update the dependency map for the block offsets on the given path.
:param path
:param target_location
"""
log.debug(
"Updating dependency map for path: {} with location: {}".format(
path, target_location
)
)
try:
for address in path:
if address in self.dependency_map:
if target_location not in self.dependency_map[address]:
self.dependency_map[address].append(target_location)
if address in self.sloads_on_path:
if target_location not in self.sloads_on_path[address]:
self.sloads_on_path[address].append(target_location)
else:
self.dependency_map[address] = [target_location]
except Z3Exception as e:
# FIXME: This should not happen unless there's a bug in laser such as a BitVec512 being generated
log.debug("Error updating dependency map: {}".format(e))
self.sloads_on_path[address] = [target_location]
def protect_path(self, path: List[int]) -> None:
"""Prevent an execution path of being pruned.
def update_sstores(self, path: List[int], target_location: object) -> None:
"""Update the dependency map for the block offsets on the given path.
:param path
:param target_location
"""
for address in path:
self.protected_addresses.add(address)
if address in self.sstores_on_path:
if target_location not in self.sstores_on_path[address]:
self.sstores_on_path[address].append(target_location)
else:
self.sstores_on_path[address] = [target_location]
def wanna_execute(self, address: int, annotation: DependencyAnnotation) -> bool:
"""Decide whether the basic block starting at 'address' should be executed.
@ -185,14 +175,25 @@ class DependencyPruner(LaserPlugin):
storage_write_cache = annotation.get_storage_write_cache(self.iteration - 1)
# Execute the block if it's marked as "protected" or doesn't yet have an entry in the dependency map.
# Skip "pure" paths that don't have any dependencies.
if address in self.protected_addresses or address not in self.dependency_map:
if address not in self.sloads_on_path:
return False
# Execute the path if there are state modifications along it that *could* be relevant
if address in self.storage_accessed_global:
for location in self.sstores_on_path:
try:
solver.get_model((location == address,))
return True
dependencies = self.dependency_map[address]
except UnsatError:
continue
# Return if *any* dependency is found
dependencies = self.sloads_on_path[address]
# Execute the path if there's any dependency on state modified in the previous transaction
for location in storage_write_cache:
for dependency in dependencies:
@ -228,13 +229,6 @@ class DependencyPruner(LaserPlugin):
def start_sym_trans_hook():
self.iteration += 1
@symbolic_vm.post_hook("CALL")
def call_hook(state: GlobalState):
annotation = get_dependency_annotation(state)
annotation.has_call = True
self.protect_path(annotation.path)
@symbolic_vm.post_hook("JUMP")
def jump_hook(state: GlobalState):
address = state.get_current_instruction()["address"]
@ -257,9 +251,10 @@ class DependencyPruner(LaserPlugin):
def sstore_hook(state: GlobalState):
annotation = get_dependency_annotation(state)
annotation.extend_storage_write_cache(
self.iteration, state.mstate.stack[-1]
)
location = state.mstate.stack[-1]
self.update_sstores(annotation.path, location)
annotation.extend_storage_write_cache(self.iteration, location)
@symbolic_vm.pre_hook("SLOAD")
def sload_hook(state: GlobalState):
@ -272,7 +267,8 @@ class DependencyPruner(LaserPlugin):
# We backwards-annotate the path here as sometimes execution never reaches a stop or return
# (and this may change in a future transaction).
self.update_dependency_map(annotation.path, location)
self.update_sloads(annotation.path, location)
self.storage_accessed_global.add(location)
@symbolic_vm.pre_hook("STOP")
def stop_hook(state: GlobalState):
@ -291,11 +287,11 @@ class DependencyPruner(LaserPlugin):
annotation = get_dependency_annotation(state)
if annotation.has_call:
self.protect_path(annotation.path)
for index in annotation.storage_loaded:
self.update_dependency_map(annotation.path, index)
self.update_sloads(annotation.path, index)
for index in annotation.storage_written:
self.update_sstores(annotation.path, index)
def _check_basic_block(address: int, annotation: DependencyAnnotation):
"""This method is where the actual pruning happens.
@ -305,7 +301,12 @@ class DependencyPruner(LaserPlugin):
"""
# Don't skip any blocks in the contract creation transaction
if self.iteration < 2:
if self.iteration < 1:
return
# Don't skip newly discovered blocks
if address not in annotation.blocks_seen:
annotation.blocks_seen.add(address)
return
if self.wanna_execute(address, annotation):
@ -335,7 +336,6 @@ class DependencyPruner(LaserPlugin):
annotation.path = [0]
annotation.storage_loaded = []
annotation.has_call = False
world_state_annotation.annotations_stack.append(annotation)
@ -344,7 +344,7 @@ class DependencyPruner(LaserPlugin):
self.iteration,
state.get_current_instruction()["address"],
state.node.function_name,
self.dependency_map,
self.sloads_on_path,
annotation.storage_written[self.iteration],
)
)

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