gnu screen crashes on ssh disconnect

classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

gnu screen crashes on ssh disconnect

Wayne Davison
In recent Cygwin versions I've had gnu screen crash if the parent ssh
connection closes before an explicit disconnect is performed. If an
orderly screen disconnect happens first, future closed connections
(after reconnecting to the screen session) no longer crash screen.

To reproduce:

I ssh into my Windows 10 host, move my .screenrc file out of the way
(to keep the config the default) and run "screen" to start up a basic
screen session. I then use the ssh close-connection key sequence
(Enter, tilde, period) to close the connection. When I log back in,
the ps command shows that screen is already dead and "screen -ls"
shows a dead screen to clean up using "screen -wipe". If I start a
fresh screen and use screen's Ctrl+A d key sequence to detach, I can
use "screen -r" to reconnect and from this point on a lost connection
no longer makes screen crash, even on future reconnects.

I haven't seen this crash on Ubuntu, but since it isn't on the same
version, I tried compiling 4.8.0 to see if that might make it crash --
it did not. I then compiled the source on Cygwin (without any
configure options) and that version has the bug, so I guess that this
is either a Cygwin issue or something weird in my Windows setup.

Is anyone else seeing this crash?

I'm attaching a cygcheck.out file that has a couple secrets elided.
I'll note that I just started to run with disable_pcon set, but it's
been crashing with and without that.

..wayne..

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple

cygcheck.out (140K) Download Attachment
Reply | Threaded
Open this post in threaded view
|

Re: gnu screen crashes on ssh disconnect

Cygwin list mailing list
On Thu, 12 Mar 2020 19:01:41 -0700
Wayne Davison wrote:

> In recent Cygwin versions I've had gnu screen crash if the parent ssh
> connection closes before an explicit disconnect is performed. If an
> orderly screen disconnect happens first, future closed connections
> (after reconnecting to the screen session) no longer crash screen.
>
> To reproduce:
>
> I ssh into my Windows 10 host, move my .screenrc file out of the way
> (to keep the config the default) and run "screen" to start up a basic
> screen session. I then use the ssh close-connection key sequence
> (Enter, tilde, period) to close the connection. When I log back in,
> the ps command shows that screen is already dead and "screen -ls"
> shows a dead screen to clean up using "screen -wipe". If I start a
> fresh screen and use screen's Ctrl+A d key sequence to detach, I can
> use "screen -r" to reconnect and from this point on a lost connection
> no longer makes screen crash, even on future reconnects.
>
> I haven't seen this crash on Ubuntu, but since it isn't on the same
> version, I tried compiling 4.8.0 to see if that might make it crash --
> it did not. I then compiled the source on Cygwin (without any
> configure options) and that version has the bug, so I guess that this
> is either a Cygwin issue or something weird in my Windows setup.
>
> Is anyone else seeing this crash?
>
> I'm attaching a cygcheck.out file that has a couple secrets elided.
> I'll note that I just started to run with disable_pcon set, but it's
> been crashing with and without that.

Thanks for the report. This seems to be a problem related to pseudo
console. I will submit a patch for this issue shortly.

--
Takashi Yano <[hidden email]>
--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Reply | Threaded
Open this post in threaded view
|

Re: gnu screen crashes on ssh disconnect

Cygwin list mailing list
> On Thu, 12 Mar 2020 19:01:41 -0700
> Wayne Davison wrote:
> > In recent Cygwin versions I've had gnu screen crash if the parent ssh
> > connection closes before an explicit disconnect is performed.

Thanks for reporting. I don't have any Cygwin hosts set up as ssh servers,
so I'm not able to test this.

> Thanks for the report. This seems to be a problem related to pseudo
> console. I will submit a patch for this issue shortly.

Awesome! I'll look for that.
Andrew

--
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple