662072 - TI+JM: crash in mjit-generated code

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jan de Mooij [:jandem]]

--
(function () {
    var x;
    x = arguments.length;
    return function () {
        [1][x = arguments.length];
    };
}).call().apply();
--
This crashes 64-bit shell with -m -n -a.

Comment 1

[Brian Hackett [Laid off!]]

During frame prologues for scripts which use their arguments, we make sure the number of actual arguments is correctly set even if nargs == nactual, to speed up accesses to arguments.length and bounds checks on arguments[i] later on.  On x64 we used a 32 bit store but would later do 64 bit arithmetic on it, so we could end up reading uninitialized high bits from the field.

http://hg.mozilla.org/projects/jaegermonkey/rev/6d423e5f2e48