Comment 17 for bug 1646181

Reviewed: https://review.openstack.org/409774
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=a859481b797048579f69e8c07b09a4628776fb1f
Submitter: Jenkins
Branch: stable/newton

commit a859481b797048579f69e8c07b09a4628776fb1f
Author: Sean Dague <email address hidden>
Date: Thu Dec 8 10:09:06 2016 -0500

    Bump prlimit cpu time for qemu from 2 to 8

    We've got user reported bugs that when opperating with slow NFS
    backends with large (30+ GB) disk files, the prlimit of cpu_time 2 is
    guessed to be the issue at hand because if folks hot patch a qemu-img
    that runs before the prlimitted one, the prlimitted one succeeds.

    This increases the allowed cpu timeout, as well as tweaking the error
    message so that we return something more prescriptive when the
    qemu-img command fails with prlimit abort.

    The original bug (#1449062) the main mitigation concern here was a
    carefully crafted image that gets qemu-img to generate > 1G of json,
    and hence could be a node attack vector. cpu_time was never mentioned,
    and I think was added originally as a belt and suspenders addition. As
    such, bumping it to 8 seconds shouldn't impact our protection in any
    real way.

    Change-Id: I1f4549b787fd3b458e2c48a90bf80025987f08c4
    Closes-Bug: #1646181
    (cherry picked from commit b78b1f8ce3aa407307a6adc5c60de1e960547897)