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    SubjectRe: [kernel-hardening] Re: [PATCH 2/2] mm: restrict access to /proc/meminfo
    On Thu, Sep 29, 2011 at 12:57 -0400, Valdis.Kletnieks@vt.edu wrote:
    > But now he has to fly blind for the next 30 because the numbers will display
    > exactly the same, and he can't correct for somebody else allocating one so he
    > needs to only allocate 29...

    You're still talking about "slabinfo", which is already restricted.


    And meminfo can be still learned with the same race window (ala seq lock):

    prepare_stuff();
    fill_slabs(); // Here we know counters with KB granularity
    while (number_is_not_ok()) {
    prepare_stuff();
    fill_slabs();
    }
    do_exploit();


    Thanks,

    --
    Vasiliy Kulikov
    http://www.openwall.com - bringing security into open computing environments


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