SSH hangs when using GPG2 + Yubikey on OS-X

[NIIBE Yutaka]

On 07/18/2016 07:44 AM, Ben Warren wrote:
> I’m using a Yubikey 4 hardware token on OS-X “Yosemite”.  I’m connecting
> to a remote Linux VM and am using GPG agent-forwarding in order to sign
> git commits using the Yubikey.  I also forward SSH through GPG, but find
> that with one or two SSH sessions open, they hang after a couple of
> hours. This time frame is sometimes shorter, but rarely longer.  In
> order to recover, I need to kill scdaemon on the Mac using SIGKILL.
>  I’ve tried SIGHUP, but that doesn’t help.
> 
> I’m able to tolerate this, but colleagues who have more open SSH
> connections open see it hang much more often to the point where this is
> unusable.

I'm not sure the symptom; which is the result and which is the cause?
I mean, scdaemon hangs because of SSH hung sessions?

Well, SIGHUP doesn't work for scdaemon.  scdaemon can be killed by:

    $ gpgconf --reload scdaemon

> gpg (GnuPG) 2.1.12
> libgcrypt 1.7.0

OK.

> ========
> Timeline:
> 2016-07-13 16:20:58 : started SSH connection
> 2016-07-13 16:30      : I noticed the SSH connection was hung and killed
> scdaemon
> 
> Here’s an interesting snippet from the log file:
> 
> 2016-07-13 16:28:00 scdaemon[32523] DBG: leave: apdu_get_status =>
> sw=0x0 status=7 changecnt=3
> 2016-07-13 16:28:01 scdaemon[32523] DBG: enter: apdu_get_status: slot=0
> hang=0
> 2016-07-13 16:28:01 scdaemon[32523] DBG: leave: apdu_get_status =>
> sw=0x0 status=7 changecnt=3
> 2016-07-13 16:28:01 scdaemon[32523] DBG: chan_6 <- RESTART
> 2016-07-13 16:28:01 scdaemon[32523] Ohhhh jeeee: trying to release an
> already released context

This is a bug of scdaemon.  I just fixed this.  This is due to the
race conditions where release_application could be called multiple
times.

	commit: 0c1fd4e9884ed7c1edd1819762b9e8a77f606ed3

But, I think that this "Ohhh jeeee" results the process of scdaemon
(PID=32523) aborted.  Do you mean, you needed to kill the another
scdaemon of PID=32745 in this case or the one of PID=32523?
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