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Restrict direct stack usage in opfns #240

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merged 2 commits into from
Dec 17, 2017
Merged

Restrict direct stack usage in opfns #240

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4d77c87
Do not manipulate stack directly in CALLs
axic Dec 15, 2017
86308eb
Manipulate the stack items directly in SWAP
axic Dec 15, 2017
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14 changes: 9 additions & 5 deletions lib/opFns.js
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Original file line number Diff line number Diff line change
Expand Up @@ -470,6 +470,8 @@ module.exports = {
return loaded
},
DUP: function (runState) {
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Actually for DUP we could change the opcodes table to say takes 1 off and pushes 2 new items, but that makes it just more complex here.

// NOTE: this function manipulates the stack directly!

const stackPos = runState.opCode - 0x7f
if (stackPos > runState.stack.length) {
trap(ERROR.STACK_UNDERFLOW)
Expand All @@ -478,6 +480,8 @@ module.exports = {
return runState.stack[runState.stack.length - stackPos]
},
SWAP: function (runState) {
// NOTE: this function manipulates the stack directly!

var stackPos = runState.opCode - 0x8f

// check the stack to make sure we have enough items on teh stack
Expand All @@ -487,9 +491,10 @@ module.exports = {
}

// preform the swap
var newTop = runState.stack[swapIndex]
runState.stack[swapIndex] = runState.stack.pop()
return newTop
var topIndex = runState.stack.length - 1
var tmp = runState.stack[topIndex]
runState.stack[topIndex] = runState.stack[swapIndex]
runState.stack[swapIndex] = tmp
},
LOG: function (memOffset, memLength) {
var args = Array.prototype.slice.call(arguments, 0)
Expand Down Expand Up @@ -1023,8 +1028,7 @@ function makeCall (runState, callOptions, localOpts, cb) {
// check if account has enough ether
// Note: in the case of delegatecall, the value is persisted and doesn't need to be deducted again
if (runState.depth >= fees.stackLimit.v || (callOptions.delegatecall !== true && new BN(runState.contract.balance).lt(callOptions.value))) {
runState.stack.push(Buffer.from([0]))
cb(null)
cb(null, Buffer.from([0]))
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I think this is the reason which makes #222 fail on calls.

} else {
// if creating a new contract then increament the nonce
if (!callOptions.to) {
Expand Down