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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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