[tor-talk] Help testing patch on SandyBridge/IvyBridge? Force disable use of RDRAND in OpenSSL when HardwareAccel is enabled

Nick Mathewson nickm at alum.mit.edu
Wed Dec 18 17:03:58 UTC 2013


On Sat, Dec 14, 2013 at 9:14 AM, coderman <coderman at gmail.com> wrote:
> this is logged as trac ticket:
>   https://trac.torproject.org/projects/tor/ticket/10402

I'm fairly sure that patch doesn't actually do anything; see comments
on #10402 (URL above) for my investigation.

Lessons I learned: Do not assume that you have really replaced an
undesirable function until you've investigated with a debugger.  Do
not assume you were using the undesirable function in the first place
until you've investigated with a debugger.  Above all, do not assume
that you understand how OpenSSL works until you have investigated with
a debugger, the source code, and a pot of coffee.

There is a probably fixed patch ready for testing at that URL that
should apply cleanly to 0.2.4. I've made a quick and dirty 0.2.5
version for people to use as well, if they like.

These could use review and testing, of course.  Comments at the above
URL if possible please.

yrs,
-- 
Nick


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