[RFC] ASLR Whitepaper and Candidate Final Patch

[Julian Elischer]

On 7/31/14, 11:00 AM, Pedro Giffuni wrote:
> Il giorno 24/lug/2014, alle ore 12:57, Shawn Webb <lattera at gmail.com> ha scritto:
>
>>
>> The unixbench results are in. The overall scores are below.
>>
>> ASLR Disabled: 456.33
>> ASLR Enabled:  357.05
>> No ASLR:       474.03

is bigger better or worse?

>>
>> I've uploaded the raw results to
>> http://0xfeedface.org/~shawn/aslr/2014-07-24_benchmark.tar.gz
>>
>> Take these results with a grain of salt, given that some of unixbench's
>> test are filesystem-related and I'm running ZFS on an old laptop with
>> little RAM. It does show that there is a performance impact when ASLR is
>> enabled.
and even from being included. I don't believe that should be forgotten.
1% here ,2% there.. soon you have lost noticeable performance.


> The effect of the available RAM and/or age of the system is
> independent of ASLR being on or off si I think the results are valid.
>
> As Robert said, the particularly bad result is the effect of having ASLR
> disabled vs not having the patch at all. The priority should certainly be
> to fix this.
>
> The effect of ASLR seems significant, I did expect it less but it is something
> that can be expected. People that enable ASLR have to be aware that there
> are consequences performance-wise. A further effect that hasn’t been quantified
> but could be obtained from the raw data is the standard deviation. I would expect
> that the randomization induced from using ASLR will cause an important increase
> in the standard deviation and that performance will be basically unpredictable.
>
> The last issue is a show stopper from enabling ASLR by default but the first
> issue is a show stopper from committing the patch at all :(.
>
> Of course, all just IMHO.
>
> Pedro.
>
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