[tor-relays] If you get weird crashes, that might be why

[Yuriy M. Kaminskiy]

On 26.06.2016 16:22, pa011 wrote:
> On start-up my Exit (Linux 3.16.0-4-amd64) Tor 0.2.7.6  creates this log
> message:
>
> [warn] OpenSSL version from headers does not match the version we're
> running with. If you get weird crashes, that might be why. (Compiled
> with 100010bf: Op$bf: OpenSSL 1.0.1k 8 Jan 2015; running with 1000114f:
                  ^^^^^^^
> OpenSSL 1.0.1t  3 May 2016).
>
> Unfortunately it really crashes ones a day. This seems to be an ongoing
> problem for years now?
>
> Could anyone please give some help - or is there none?

No, this is NOT a reason for those crashes.

Background:
At May/June 2016, Debian jessie transitioned from heavily-patched 
openssl 1.0.1k (with a lot of security patches backported from later 
[stable] versions) to (much more lightly-patched) openssl 1.0.1t (which 
already included all those security fixes).

Both versions are (supposed to be) completely binary compatible, and 
running a binary compiled against 1.0.1k with openssl 1.0.1t should be 
completely safe.

If your tor crashes daily (and especially if that also happened before 
June 2016, when debian transitioned to 1.0.1t), the reason must be 
something else (hardware problem, insufficient resources [memory? disk? 
process/task/thread limit?], some obscure tor bug).

That said, above message looks weird. It comes from this code:

log_warn(LD_CRYPTO, "OpenSSL version from headers does not match the "
        "version we're running with. If you get weird crashes, that "
        "might be why. (Compiled with %lx: %s; running with %lx: %s).",
        (unsigned long)OPENSSL_VERSION_NUMBER, OPENSSL_VERSION_TEXT,
        SSLeay(), SSLeay_version(SSLEAY_VERSION));

What is that "Op$bf: " in above message and where it comes from?