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SubjectRe: [PATCH 07/12] perf_events: add LBR software filter support for Intel X86

* Andi Kleen <andi@firstfloor.org> wrote:

> On Thu, Oct 06, 2011 at 06:43:44PM +0200, Peter Zijlstra wrote:
> > On Thu, 2011-10-06 at 17:32 +0200, Andi Kleen wrote:
> > > > + kernel_insn_init(&insn, kaddr);
> > > > + insn_get_opcode(&insn);
> > >
> > > This makes me uncomfortable. AFAIK that's the first use of the opcode
> > > decoder being used directly for user space. It has a quite large attack
> > > surface. Who says it cannot be exploited?
> >
> > You mean:
> > arch/x86/kernel/cpu/perf_event_intel_ds.c:intel_pmu_pebs_fixup_ip()
> > doesn't use the opcode decoder on user space code?
>
> True it does. Ok the second.

That's what matters.

> I know uprobes is planning it too, so the problem has to be handled
> eventually.
>
> Still it makes me uncomfortable.

FUD is not how we approach these things - you need to say something
specific.

Thanks,

Ingo


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