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Stuffing the return stack buffer

Stuffing the return stack buffer

Posted Jul 23, 2022 14:47 UTC (Sat) by Paf (subscriber, #91811)
In reply to: Stuffing the return stack buffer by Paf
Parent article: Stuffing the return stack buffer

Specifically, at context switches. So this looks to be only truly applicable on a system where cores are entirely independent or there’s just one core. This looks like a very limited mitigation and not much applicable to the larger cores we work with. It also relies on knowing what “all micro architecture state” is - part of the steady march of these issues has been people finding things that weren’t previously recognized as “state” worthy of protecting.

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Stuffing the return stack buffer

Posted Jul 23, 2022 16:26 UTC (Sat) by epa (subscriber, #39769) [Link]

...or somehow you arrange for all the cores sharing a cache to be running code from the same protection domain at the same time. When one context switches to a different user or to the kernel, they all must.

Stuffing the return stack buffer

Posted Jul 24, 2022 20:19 UTC (Sun) by Sesse (subscriber, #53779) [Link] (1 responses)

So all your syscalls are now basically as expensive as you can possibly make them?

Stuffing the return stack buffer

Posted Jul 24, 2022 23:03 UTC (Sun) by Paf (subscriber, #91811) [Link]

I mean, they talk about how to make that specific operation more efficient and it could be worse, but …….. yes.


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