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mythril
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Modifies the symbolic suffixes enclosing them into brackets and symplifying them with the z3 simplification algorithm

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pull/310/head
Konrad Weiss 7 years ago
parent dc0e93566a
commit 06ddeb13dc
1 changed files with 20 additions and 15 deletions
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  1. 35
      mythril/laser/ethereum/svm.py

35
mythril/laser/ethereum/svm.py
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@ -396,7 +396,7 @@ class LaserEVM:
result = Concat(BitVecVal(0, 248), Extract(oft + 7, oft, s1)) result = Concat(BitVecVal(0, 248), Extract(oft + 7, oft, s1))
except AttributeError: except AttributeError:
logging.debug("BYTE: Unsupported symbolic byte offset") logging.debug("BYTE: Unsupported symbolic byte offset")
result = BitVec(str(simplify(s1)) + "_" + str(simplify(s0)), 256) result = BitVec(str(simplify(s1)) + "[" + str(simplify(s0)) + "]", 256)
state.stack.append(simplify(result)) state.stack.append(simplify(result))
@ -442,7 +442,7 @@ class LaserEVM:
base, exponent = helper.pop_bitvec(state), helper.pop_bitvec(state) base, exponent = helper.pop_bitvec(state), helper.pop_bitvec(state)
if (type(base) != BitVecNumRef) or (type(exponent) != BitVecNumRef): if (type(base) != BitVecNumRef) or (type(exponent) != BitVecNumRef):
state.stack.append(BitVec(str(base) + "_EXP_" + str(exponent), 256)) state.stack.append(BitVec("(" + str(simplify(base)) + ")^(" + str(simplify(exponent)) + ")", 256))
elif (base.as_long() == 2): elif (base.as_long() == 2):
if exponent.as_long() == 0: if exponent.as_long() == 0:
state.stack.append(BitVecVal(1, 256)) state.stack.append(BitVecVal(1, 256))
@ -535,11 +535,11 @@ class LaserEVM:
except AttributeError: except AttributeError:
logging.debug("CALLDATALOAD: Unsupported symbolic index") logging.debug("CALLDATALOAD: Unsupported symbolic index")
state.stack.append(BitVec("calldata_" + str(environment.active_account.contract_name) + "_" + str(op0), 256)) state.stack.append(BitVec("calldata_" + str(environment.active_account.contract_name) + "[" + str(simplify(op0)) + "]", 256))
continue continue
except IndexError: except IndexError:
logging.debug("Calldata not set, using symbolic variable instead") logging.debug("Calldata not set, using symbolic variable instead")
state.stack.append(BitVec("calldata_" + str(environment.active_account.contract_name) + "_" + str(op0), 256)) state.stack.append(BitVec("calldata_" + str(environment.active_account.contract_name) + "[" + str(simplify(op0)) + "]", 256))
continue continue
if type(b) == int: if type(b) == int:
@ -554,10 +554,10 @@ class LaserEVM:
state.stack.append(BitVecVal(int.from_bytes(val, byteorder='big'), 256)) state.stack.append(BitVecVal(int.from_bytes(val, byteorder='big'), 256))
except: except:
state.stack.append(BitVec("calldata_" + str(environment.active_account.contract_name) + "_" + str(op0), 256)) state.stack.append(BitVec("calldata_" + str(environment.active_account.contract_name) + "[" + str(simplify(op0)) + "]", 256))
else: else:
# symbolic variable # symbolic variable
state.stack.append(BitVec("calldata_" + str(environment.active_account.contract_name) + "_" + str(op0), 256)) state.stack.append(BitVec("calldata_" + str(environment.active_account.contract_name) + "[" + str(simplify(op0)) + "]", 256))
elif op == 'CALLDATASIZE': elif op == 'CALLDATASIZE':
@ -575,20 +575,25 @@ class LaserEVM:
logging.debug("Unsupported symbolic memory offset in CALLDATACOPY") logging.debug("Unsupported symbolic memory offset in CALLDATACOPY")
continue continue
dstart_sym = False
try: try:
dstart = helper.get_concrete_int(op1) dstart = helper.get_concrete_int(op1)
dstart_sym = True
except: except:
logging.debug("Unsupported symbolic calldata offset in CALLDATACOPY") logging.debug("Unsupported symbolic calldata offset in CALLDATACOPY")
state.mem_extend(mstart, 1) dstart = simplify(op1)
state.memory[mstart] = BitVec("calldata_" + str(environment.active_account.contract_name) + "_cpy", 256)
continue
size_sym = False
try: try:
size = helper.get_concrete_int(op2) size = helper.get_concrete_int(op2)
size_sym = True
except: except:
logging.debug("Unsupported symbolic size in CALLDATACOPY") logging.debug("Unsupported symbolic size in CALLDATACOPY")
size = simplify(op2)
if dstart_sym or size_sym:
state.mem_extend(mstart, 1) state.mem_extend(mstart, 1)
state.memory[mstart] = BitVec("calldata_" + str(environment.active_account.contract_name) + "_" + str(dstart), 256) state.memory[mstart] = BitVec("calldata_" + str(environment.active_account.contract_name) + "[" + str(dstart) + ": + " + str(size) + "]", 256)
continue continue
if size > 0: if size > 0:
@ -598,7 +603,7 @@ class LaserEVM:
except: except:
logging.debug("Memory allocation error: mstart = " + str(mstart) + ", size = " + str(size)) logging.debug("Memory allocation error: mstart = " + str(mstart) + ", size = " + str(size))
state.mem_extend(mstart, 1) state.mem_extend(mstart, 1)
state.memory[mstart] = BitVec("calldata_" + str(environment.active_account.contract_name) + "_" + str(dstart), 256) state.memory[mstart] = BitVec("calldata_" + str(environment.active_account.contract_name) + "[" + str(dstart) + ": + " + str(size) + "]", 256)
continue continue
try: try:
@ -610,7 +615,7 @@ class LaserEVM:
except: except:
logging.debug("Exception copying calldata to memory") logging.debug("Exception copying calldata to memory")
state.memory[mstart] = BitVec("calldata_" + str(environment.active_account.contract_name) + "_" + str(dstart), 256) state.memory[mstart] = BitVec("calldata_" + str(environment.active_account.contract_name) + "[" + str(dstart) + ": + " + str(size) + "]", 256)
elif op == 'STOP': elif op == 'STOP':
if len(self.call_stack): if len(self.call_stack):
@ -645,7 +650,7 @@ class LaserEVM:
except: except:
# Can't access symbolic memory offsets # Can't access symbolic memory offsets
state.stack.append(BitVec("KECCAC_mem_" + str(op0) + ")", 256)) state.stack.append(BitVec("KECCAC_mem[" + str(simplify(op0)) + "]", 256))
continue continue
try: try:
@ -717,14 +722,14 @@ class LaserEVM:
offset = helper.get_concrete_int(op0) offset = helper.get_concrete_int(op0)
except AttributeError: except AttributeError:
logging.debug("Can't MLOAD from symbolic index") logging.debug("Can't MLOAD from symbolic index")
data = BitVec("mem_" + str(op0), 256) data = BitVec("mem[" + str(simplify(op0)) + "]", 256)
state.stack.append(data) state.stack.append(data)
continue continue
try: try:
data = helper.concrete_int_from_bytes(state.memory, offset) data = helper.concrete_int_from_bytes(state.memory, offset)
except IndexError: # Memory slot not allocated except IndexError: # Memory slot not allocated
data = BitVec("mem_" + str(offset), 256) data = BitVec("mem[" + str(offset)+"]", 256)
except TypeError: # Symbolic memory except TypeError: # Symbolic memory
data = state.memory[offset] data = state.memory[offset]

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