Messages in this thread | | | Date | Thu, 14 Feb 2008 13:00:03 -0800 | From | Arjan van de Ven <> | Subject | Re: [x86.git#mm] stack protector fixes, vmsplice exploit |
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On Thu, 14 Feb 2008 21:25:35 +0100 Ingo Molnar <mingo@elte.hu> wrote:
> > * pageexec@freemail.hu <pageexec@freemail.hu> wrote: > > > really, the best defense is to reduce the useful lifetime of any > > leaked canary, and you can't get better than syscall granularity > > without disproportional effort and impact elsewhere (and i'm sure > > some would find even this disproportional ;). > > hm, i think per syscall canaries are really expensive.
it's not that bad. Assuming you use a PNR that you re-seed periodically, it's * go to the next random number with PNR * write to PDA and task struct
give or take 10 cycles total if you squeeze it hard, 20 if you don't.
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