Messages in this thread | | | Date | Tue, 29 Apr 2014 21:57:46 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 4/7] x86: Add support for rd/wr fs/gs base |
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On 04/29/2014 09:52 PM, H. Peter Anvin wrote: > > It matters -- greatly -- if (and only if) we can enter the kernel with > usergs == kernelgs and then want to change usergs inside a paranoid > routine. At that point we risk being upside down, which basically means > we're rooted. > > However, I believe this patchset also means only IST entries can be > paranoid, which in turn means we can't sleep inside them. To the very > best of my knowledge the only times we change usergs is on context > switch or inside a system call. We need to make sure that is actually > the case, though. > > I'm at ELC for a few days, so I'll have limited decent-sized-monitor > time, but it shouldn't be too hard to convince ourselves of... mostly a > matter of making sure something like ptrace can't to stupid crap. >
Just in case anyone is getting the wrong impression: this is a discussion about details. I'm glad to see this work getting done.
-hpa
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