Re: [PATCH prototype] [0/8] Predictive bitmaps for ELF executables

Pavel Machek
2008-03-25T14:43:22Z

On Sun 2008-03-23 18:08:27, Andi Kleen wrote:
> > Is this good idea? Attacker can send you binary with the bitmap
> > inverted, it is now slow on your system and signature matches.
>
> The first run will fix up any missing bits in the bitmap. Right
> now it cannot get rid of unnecessary pages though unless you
> disable early_fault.
>
> > ...might be important for benchmarks... 'here, see, Oracle is slow.
> > Feel free to verify the signature'.
> >
> > ...ok, I guess it is not too serious, because it is similar to
> > fragmentation....
>
> It is actually far better than fragmentation because the bitmap
> loader does IO always in big chunks -- not much seeking will go on.
> The only problem is some wasted mmeory and more IO bandwidth
> usage (but typically binaries are not bigger than a few MB so
> it's not too dramatic)
>
> So in summary I don't think it's an issue.

Agreed.

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