Rewrite 'unchecked_retval' module

mythril/analysis/modules/unchecked_retval.py

@@ -1,9 +1,7 @@
-from z3 import *
-import re
-from mythril.analysis.ops import *
 from mythril.analysis.report import Issue
+from laser.ethereum.svm import NodeFlags
 import logging
-from laser.ethereum import helper
+import re
 
 
 '''
@@ -30,54 +28,66 @@ def execute(statespace):
     logging.debug("Executing module: UNCHECKED_RETVAL")
 
     issues = []
-    visited = []
 
-    for call in statespace.calls:
+    for k in statespace.nodes:
+
+        node = statespace.nodes[k]
+
+        if NodeFlags.CALL_RETURN in node.flags:
+
+            retval_checked = False
+
+            for state in node.states:
+
+                instr = state.get_current_instruction()
+
+                if (instr['opcode'] == 'ISZERO' and re.search(r'retval', str(state.mstate.stack[-1]))):
+                    retval_checked = True
+                    break
+
+            if not retval_checked:
 
-        state = call.state
                 address = state.get_current_instruction()['address']
+                issue = Issue(node.contract_name, node.function_name, address, "Unchecked CALL return value")
+
+                issue.description = \
+                    "The return value of an external call is not checked. Note that the contract will continue if the call fails."
 
-        # Only needs to be checked once per call instructions (it's essentially just static analysis)
+                issues.append(issue)
 
-        if call.state.mstate.pc in visited:
-            continue
         else:
-            visited.append(call.state.mstate.pc)
 
-        retval_checked = False
+            nStates = len(node.states)
 
-        # ISZERO retval is expected to be found within the next few instructions.
+            for idx in range(0, nStates):
 
-        for i in range(0, 10):
+                state = node.states[idx]
+                instr = state.get_current_instruction()
 
-            _state = call.node.states[call.state_index + i]
+                if (instr['opcode'] == 'CALL'):
+
+                    retval_checked = False
+
+                    for _idx in range(idx, idx + 10):
 
                         try:
-                instr = _state.get_current_instruction()
-            except IndexError:
-                break
+                            _state = node.states[_idx]
+                            _instr = _state.get_current_instruction()
 
-            if (instr['opcode'] == 'ISZERO' and re.search(r'retval', str(_state.mstate.stack[-1]))):
+                            if (_instr['opcode'] == 'ISZERO' and re.search(r'retval', str(_state .mstate.stack[-1]))):
                                 retval_checked = True
                                 break
 
-        if not retval_checked:
-
-            issue = Issue(call.node.contract_name, call.node.function_name, address, "Unchecked CALL return value")
+                        except IndexError:
+                            break
 
-            if (call.to.type == VarType.CONCRETE):
-                receiver = hex(call.to.val)
-            elif (re.search(r"caller", str(call.to))):
-                receiver = "msg.sender"
-            elif (re.search(r"storage", str(call.to))):
-                receiver = "an address obtained from storage"
-            else:
-                receiver = str(call.to)
+                    if not retval_checked:
 
+                        address = instr['address']
+                        issue = Issue(node.contract_name, node.function_name, address, "Unchecked CALL return value")
 
                         issue.description = \
-                "The function " + call.node.function_name + " contains a call to " + receiver + ".\n" \
-                "The return value of this call is not checked. Note that the function will continue to execute with a return value of '0' if the called contract throws."
+                            "The return value of an external call is not checked. Note that execution continue even if the called contract throws."
 
                         issues.append(issue)
 

solidity_examples/reentrancy.sol

@@ -12,9 +12,7 @@ contract Reentrancy {
 
   function withdraw(uint _amount) public {
     if(balances[msg.sender] >= _amount) {
-      if(msg.sender.call.value(_amount)()) {
-        _amount;
-      }
+      msg.sender.call.value(_amount)();
       balances[msg.sender] -= _amount;
     }
   }

solidity_examples/returnvalue.sol

@@ -0,0 +1,19 @@
+contract ReturnValue {
+
+  address callee = 0xE0F7e56e62b4267062172495D7506087205A4229;
+
+  function call1() returns (uint256) {
+    callee.call();
+  }
+
+  function call2() returns (uint256) {
+
+    
+  }
+
+  function call3() returns (uint256) {
+
+    
+  }
+
+}