[RFC] ASLR Whitepaper and Candidate Final Patch

[Pedro Giffuni]

Il giorno 23/lug/2014, alle ore 18:44, Shawn Webb <lattera at gmail.com> ha scritto:

> On Jul 23, 2014 06:37 PM -0500, Pedro Giffuni wrote:
>> Hi;
>> 
>> Il giorno 22/lug/2014, alle ore 19:45, Shawn Webb <lattera at gmail.com> ha scritto:
>> 
>>>>> ...
>>>> 
>>>> Hi Shawn:
>>>> 
>>>> Great news that this work is coming to fruition -- ASLR is long overdue.
>>>> 
>>>> Are you having any luck with performance measurements?  Unixbench seems like a 
>>>> good starting point, but I wonder if it would be useful to look, in 
>>>> particular, at memory-mapping intensive workloads that might be affected as a 
>>>> result of changes in kernel VM data-structure use, or greater fragmentation of
>>>> the address space.  I'm not sure I have a specific application here in mind -- 
>>>> in the past I might have pointed out tools such as ElectricFence that tend to 
>>>> increase fragmentation themselves.
>>> 
>>> The unixbench tests on that laptop have finished. However, I've been
>>> fighting a pesky migraine these last couple days, so I haven't had the
>>> opportunity to aggregate the results into a nice little spreadsheet. I'm
>>> hoping to finish it up by the end of the week.
>>> 
>>> I'll take a look at ElectricFence this weekend. Additionally, I have a
>>> netbook somewhere. Once I find it and its power cord, I'll install
>>> FreeBSD/x86 and re-run the same tests on that.
>>> 
>> 
>> Somewhat related to ElectricFence? will ASLR have an adverse effect on debuggers?
>> 
>> I googled around and got to this:
>> 
>> http://www.outflux.net/blog/archives/2010/07/03/gdb-turns-off-aslr/
> 
> I've been doing all my ClamAV development on my FreeBSD box with ASLR
> enabled. Development tools like gdb and valgrind work great, even with
> corefiles. I have not, however, tried lldb.
> 

OK, but it’s worth to take a look if we need to support something to turn it off.
Apparently gdb disables ASLR on MacOSX too:

http://reverse.put.as/2011/08/11/how-gdb-disables-aslr-in-mac-os-x-lion/

Pedro.