Validate stack items after operations

ethereumjs · Oct 13, 2017 · 462d5ad · 462d5ad
1 parent 7c357fd
commit 462d5ad
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Showing 2 changed files with 30 additions and 4 deletions.
diff --git a/lib/constants.js b/lib/constants.js
@@ -5,5 +5,6 @@ exports.ERROR = {
   INVALID_JUMP: 'invalid JUMP',
   INVALID_OPCODE: 'invalid opcode',
   REVERT: 'revert',
-  STATIC_STATE_CHANGE: 'static state change'
+  STATIC_STATE_CHANGE: 'static state change',
+  INTERNAL_ERROR: 'internal error'
 }
diff --git a/lib/runCode.js b/lib/runCode.js
@@ -165,11 +165,14 @@ module.exports = function (opts, cb) {
         cb()
         return
       }
+
       // advance program counter
       runState.programCounter++
       var argsNum = opInfo.in
+      var retNum = opInfo.out
       // pop the stack
-      var args = argsNum ? runState.stack.splice(-opInfo.in) : []
+      var args = argsNum ? runState.stack.splice(-argsNum) : []
+
       args.reverse()
       args.push(runState)
       // create a callback for async opFunc
@@ -178,11 +181,22 @@ module.exports = function (opts, cb) {
           if (err) return cb(err)
 
           // save result to the stack
-          if (result) {
+          if (result !== undefined) {
+            if (retNum != 1) {
+              // opcode post-stack mismatch
+              runState.vmError = ERROR.INTERNAL_ERROR
+              cb()
+              return
+            }
             // NOTE: Ensure that every stack item is padded to 256 bits.
             //       This should be done at every opcode in the future.
             result = utils.setLengthLeft(result, 32)
             runState.stack.push(result)
+          } else if (retNum != 0) {
+            // opcode post-stack mismatch
+            runState.vmError = ERROR.INTERNAL_ERROR
+            cb()
+            return
           }
 
           cb()
@@ -199,11 +213,22 @@ module.exports = function (opts, cb) {
       }
 
       // save result to the stack
-      if (result) {
+      if (result !== undefined) {
+        if (retNum != 1) {
+          // opcode post-stack mismatch
+          runState.vmError = ERROR.INTERNAL_ERROR
+          cb()
+          return
+        }
         // NOTE: Ensure that every stack item is padded to 256 bits.
         //       This should be done at every opcode in the future.
         result = utils.setLengthLeft(result, 32)
         runState.stack.push(result)
+      } else if (retNum != 0) {
+        // opcode post-stack mismatch
+        runState.vmError = ERROR.INTERNAL_ERROR
+        cb()
+        return
       }
 
       // call the callback if opFn was sync