[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20141205205916.37658ede@pc>
Date: Fri, 5 Dec 2014 20:59:16 +0100
From: Hanno Böck <hanno@...eck.de>
To: oss-security@...ts.openwall.com
Subject: Re: Offset2lib: bypassing full ASLR on 64bit Linux
Okay, I'm surprised to see that while everyone seems to claim
performance reasons are why we don't use fpic/pie by default I can't
find anyone actually benchmarking it.
*disclaimer: benchmarking is tricky business, I don't know if I messed
something up. If you feel this is a completely wrong way to benchmark
this I'm open to suggestions. *
I decided a reasonable target would be a static compile of ffmpeg,
because it does some complicated stuff.
I compiled two copies mostly identical with the difference that for one
I passed CFLAGS="-O2" LDFLAGS="" while for the other I passed
CFLAGS="-O2 -fpic" LDFLAGS="-pie".
I then converted a h264 video to mpeg4.
This is what I got:
no pie/pic: 14.664, 14.606, 14.685, 14.719, 14.69, average: 14.6728
pie/pic: 14.776, 14.951, 14.947, 14.798, 14.898, average: 14.874
So it seems the difference is at least measurable (around 1,4%) but not
big.
I haven't benchmarked with the patches Florian referred to, they
involve patching gold and gcc (the above is done with classic ld).
--
Hanno Böck
http://hboeck.de/
mail/jabber: hanno@...eck.de
GPG: BBB51E42
Content of type "application/pgp-signature" skipped
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
