Requirements

• Node

Setup

Install ganache-cli, solc, and web3 via npm, i.e., npm install ganache-cli web3 solc --save

Reproducing

In another terminal window, begin the ganache test client: ./node_modules/.bin/ganache-cli

Then, in this directory, simply run node index.js.

You should see something like the following output

helogale:InvalidCalldataPOC jrw$ node index.js
Done compiling
Deployed exploitable contract
0

The return value of 0 indicates that the calldata validation code did not correctly revert, and instead "zero padded" the nested arrays in calldata. The leaf of the call tree, doIt faithfully reads the 0's inserted by the call in outer.