Messages in this thread | | | Date | Tue, 9 Nov 2010 11:19:08 -0800 | From | Kees Cook <> | Subject | Re: [PATCH 3/4] x86: call verify_cpu during 32bit CPU startup |
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On Tue, Nov 09, 2010 at 09:09:18PM +0200, Pekka Enberg wrote: > On Tue, Nov 9, 2010 at 8:15 PM, Kees Cook <kees.cook@canonical.com> wrote: > > The XD_DISABLE-clearing side-effect needs to happen on 32bit CPU > > start-up as well. > > > > Signed-off-by: Kees Cook <kees.cook@canonical.com> > > The patch description here is pretty damn terse. Why do we need the > clearing for? Does not clearing XD_DISABLE cause some problem?
The clearing needs to happen for both 32bit and 64bit, but the 32bit init routines were not calling verify_cpu() yet. This adds that path to gain the side-effect. (See patch 0 for why clearing XD_DISABLE is important.)
-- Kees Cook Ubuntu Security Team
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