GCC and Meltdown and Spectre vulnerabilities

[Ian Lance Taylor via gcc]

On Thu, Jan 4, 2018 at 7:14 PM, Zan Lynx <zlynx@acm.org> wrote:
>
> On January 4, 2018 8:10:14 PM MST, Eric Gallager <egall@gwmail.gwu.edu> wrote:
>>Is there anything GCC could be doing at the compiler level to mitigate
>>the recently-announced Meltdown and Spectre vulnerabilities? From
>>reading about them, it seems like they involve speculative execution
>>and indirect branch prediction, and those are the domain of things the
>>compiler deals with, right? (For reference, Meltdown is CVE-2017-5754,
>>and Spectre is CVE-2017-5753 and CVE-2017-5715)
>>
>>Just wondering,
>>Eric
>
> If you're allowing people to run untrustworthy machine code on your hardware there's nothing a compiler can do to help. You'd need to make them use your compiler, and why would they?
>
> So anyone offering shell accounts or virtual machines is out of luck.

For the Spectre attack, a compiler can help by using it to compile
accessible programs in such a way that they are not vulnerable to the
attack.

Ian