[Public WebGL] EXT_disjoint_timer_query disabled

Florian Bösch [email protected]
Sun May 13 10:50:59 PDT 2018

20 years on writing hardware accelerated code we have no way to measure the
performance of the programs we write, on the machines our users use to run
these programs. You've got to be fucking kidding me man.

On Sun, May 13, 2018 at 6:48 PM, Aleksandar Rodic <[email protected]>

> My guess is the extension has been disabled due to recently discovered "
> GLitch <https://www.vusec.net/wp-content/uploads/2018/05/glitch.pdf>"
> rowhammer attack vector.
> > EXT_DISJOINT_TIMER_QUERY is an OpenGL extension developed to provide
> developers with more detailed information about the performance of their
> applications [46]. This extension, if made available to the system by the
> GPU driver, is accessible from both WebGL and WebGL2, and provides the
> JavaScript runtime with two timing sources: (1) TIME_ELAPSED_EXT and (2)
> TIMESTAMP_EXT. Such timers allow an attacker to measure the timing of
> secret operations (e.g., memory accesses) performed either by the CPU or
> the GPU.
> On Sun, May 13, 2018 at 4:32 PM Florian Bösch <[email protected]> wrote:
>> On Fri, Apr 6, 2018 at 12:50 AM, Ken Russell <[email protected]> wrote:
>>> We can not currently discuss why the extension has been disabled. We
>>> should be able to do so in about a month.
>> It's now been a month and a week since this statement.
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