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Meltdown/Spectre mitigation for 4.15 and beyond

Meltdown/Spectre mitigation for 4.15 and beyond

Posted Jan 15, 2018 22:55 UTC (Mon) by roc (subscriber, #30627)
Parent article: Meltdown/Spectre mitigation for 4.15 and beyond

> After all of this work, it would appear that the 4.15 kernel will be released with fairly complete Meltdown and Spectre protection

Isn't this an overstatement considering that thoroughly protecting the kernel against Spectre variant 1 requires using the new array-index macro everywhere it's needed, and no-one actually knows yet how to determine where it's needed?

Another source of confusion is that some people will interpret the above statement to mean that userspace is protected when running on the right kernel, when that is definitely not the case. This is similar to how the cloud providers quickly announced "we've fixed everything in our cloud!" when in fact they only fixed specific hypervisor-related issues and customers still have a ton of work to do.


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Meltdown/Spectre mitigation for 4.15 and beyond

Posted Jan 15, 2018 23:39 UTC (Mon) by pbonzini (subscriber, #60935) [Link]

There is work on using static analysis to place the new macro. But yes, at this point it's a whack-a-mole game.

Meltdown/Spectre mitigation for 4.15 and beyond

Posted Jan 16, 2018 0:18 UTC (Tue) by corbet (editor, #1) [Link] (1 responses)

Yeah, OK, that probably wasn't the best thing I ever wrote. In my poor defense I'll say that I was awfully tired by the time I got to the end of all that stuff...

Meltdown/Spectre mitigation for 4.15 and beyond

Posted Jan 16, 2018 2:20 UTC (Tue) by roc (subscriber, #30627) [Link]

Sorry! Amidst all the confusion, overall you're doing a great job. Thanks!


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