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    SubjectRe: [PATCH] [RFC] Introduce mmap randomization
    Hi William,

    On Tue, Jul 26, 2016 at 08:13:23PM +0000, Roberts, William C wrote:
    > > > From: Jason Cooper [mailto:jason@lakedaemon.net]
    > > > On Tue, Jul 26, 2016 at 11:22:26AM -0700, william.c.roberts@intel.com wrote:
    > > > > Performance Measurements:
    > > > > Using strace with -T option and filtering for mmap on the program ls
    > > > > shows a slowdown of approximate 3.7%
    > > >
    > > > I think it would be helpful to show the effect on the resulting object code.
    > >
    > > Do you mean the maps of the process? I have some captures for whoopsie on my
    > > Ubuntu system I can share.

    No, I mean changes to mm/mmap.o.

    > > One thing I didn't make clear in my commit message is why this is good. Right
    > > now, if you know An address within in a process, you know all offsets done with
    > > mmap(). For instance, an offset To libX can yield libY by adding/subtracting an
    > > offset. This is meant to make rops a bit harder, or In general any mapping offset
    > > mmore difficult to find/guess.

    Are you able to quantify how many bits of entropy you're imposing on the
    attacker? Is this a chair in the hallway or a significant increase in
    the chances of crashing the program before finding the desired address?

    thx,

    Jason.

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