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    SubjectRe: [PATCH 00/18] prevent bounds-check bypass via speculative execution
    On Mon, Jan 08, 2018 at 11:43:42AM +0000, Alan Cox wrote:
    > On Mon, 8 Jan 2018 11:08:36 +0100
    > Peter Zijlstra <peterz@infradead.org> wrote:
    >
    > > On Fri, Jan 05, 2018 at 10:30:16PM -0800, Dan Williams wrote:
    > > > On Fri, Jan 5, 2018 at 6:22 PM, Eric W. Biederman <ebiederm@xmission.com> wrote:
    > > > > In at least one place (mpls) you are patching a fast path. Compile out
    > > > > or don't load mpls by all means. But it is not acceptable to change the
    > > > > fast path without even considering performance.
    > > >
    > > > Performance matters greatly, but I need help to identify a workload
    > > > that is representative for this fast path to see what, if any, impact
    > > > is incurred. Even better is a review that says "nope, 'index' is not
    > > > subject to arbitrary userspace control at this point, drop the patch."
    > >
    > > I think we're focussing a little too much on pure userspace. That is, we
    > > should be saying under the attackers control. Inbound network packets
    > > could equally be under the attackers control.
    >
    > Inbound network packets don't come with a facility to read back and do
    > cache timimg.

    But could they not be used in conjunction with a local task to prime the
    stuff?

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