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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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