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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 6 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))
except AttributeError:
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))
@ -442,7 +442,7 @@ class LaserEVM:
base, exponent = helper.pop_bitvec(state), helper.pop_bitvec(state)
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):
if exponent.as_long() == 0:
state.stack.append(BitVecVal(1, 256))
@ -535,11 +535,11 @@ class LaserEVM:
except AttributeError:
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
except IndexError:
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
if type(b) == int:
@ -554,10 +554,10 @@ class LaserEVM:
state.stack.append(BitVecVal(int.from_bytes(val, byteorder='big'), 256))
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:
# 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':
@ -575,20 +575,25 @@ class LaserEVM:
logging.debug("Unsupported symbolic memory offset in CALLDATACOPY")
continue
dstart_sym = False
try:
dstart = helper.get_concrete_int(op1)
dstart_sym = True
except:
logging.debug("Unsupported symbolic calldata offset in CALLDATACOPY")
state.mem_extend(mstart, 1)
state.memory[mstart] = BitVec("calldata_" + str(environment.active_account.contract_name) + "_cpy", 256)
continue
dstart = simplify(op1)
size_sym = False
try:
size = helper.get_concrete_int(op2)
size_sym = True
except:
logging.debug("Unsupported symbolic size in CALLDATACOPY")
size = simplify(op2)
if dstart_sym or size_sym:
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
if size > 0:
@ -598,7 +603,7 @@ class LaserEVM:
except:
logging.debug("Memory allocation error: mstart = " + str(mstart) + ", size = " + str(size))
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
try:
@ -610,7 +615,7 @@ class LaserEVM:
except:
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':
if len(self.call_stack):
@ -645,7 +650,7 @@ class LaserEVM:
except:
# 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
try:
@ -717,14 +722,14 @@ class LaserEVM:
offset = helper.get_concrete_int(op0)
except AttributeError:
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)
continue
try:
data = helper.concrete_int_from_bytes(state.memory, offset)
except IndexError: # Memory slot not allocated
data = BitVec("mem_" + str(offset), 256)
data = BitVec("mem[" + str(offset)+"]", 256)
except TypeError: # Symbolic memory
data = state.memory[offset]

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