Messages in this thread | | | Date | Tue, 9 Nov 2010 10:56:04 -0800 | From | Kees Cook <> | Subject | Re: [Security] [PATCH v3 0/4] x86: clear XD_DISABLED flag on Intel to regain NX |
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On Tue, Nov 09, 2010 at 06:31:42PM +0000, Alan Cox wrote: > > In a review[1] of reported hardware being used by Ubuntu bug reporters, > > almost 10% of systems had an incorrectly configured BIOS, leaving their > > systems unable to use the NX features of their CPU. > > Ouch
Yeah :(
> > This change will clear the MSR_IA32_MISC_ENABLE_XD_DISABLE bit so that NX > > cannot be inappropriately controlled by the BIOS on Intel CPUs. If, under > > very strange hardware configurations, NX actually needs to be disabled, > > "noexec=off" can be used to restore the prior behavior. > > Have you done an audit of CPU errata to ensure that none of these cases > are ones where the BIOS has disabled it to avoid an erratum. I'd hate to > turn it on and find out the BIOS actually turned it off for good reason !
Where can I find those details?
-Kees
-- Kees Cook Ubuntu Security Team
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