[RFC] ASLR Whitepaper and Candidate Final Patch

[Shawn Webb]

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.

> 
> So I guess we may have to patch gdb (and lldb)?

From my experience with ClamAV development, I don't think so. gdb uses
ptrace to get and set the registers, so ASLR doesn't matter.

> 
> Pedro.
> 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.freebsd.org/pipermail/freebsd-arch/attachments/20140723/79ca5172/attachment.sig>