Messages in this thread | | | Date | Fri, 27 Jan 2012 23:37:26 +0400 | From | Vasiliy Kulikov <> | Subject | Re: [RFC c/r 2/4] [RFC] syscalls, x86: Add __NR_kcmp syscall v7 |
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Hi Cyrill,
On Fri, Jan 27, 2012 at 21:53 +0400, Cyrill Gorcunov wrote: > +/* > + * We don't expose real in-memory order of objects for security > + * reasons, still the comparision results should be suitable for > + * sorting. Thus, we obfuscate kernel pointers values (using random > + * cookies obtaned at early boot stage) and compare the production > + * instead. > + */ > +static unsigned long cookies[KCMP_TYPES][2] __read_mostly; > + > +static long kptr_obfuscate(long v, int type) > +{ > + return (v ^ cookies[type][0]) * cookies[type][1];
AFACS, cookies is fully random value, is it possible that
((v1 ^ cookies[type][0]) * cookies[type][1] == (v2 ^ cookies[type][0]) * cookies[type][1]) && (v1 != v2)
for too round cookies[type][1]?
Thanks,
-- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments
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