Debian Bug report logs - #393704
interactive client dies on ill-timed SIGWINCH

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Ian Jackson <ian@davenant.greenend.org.uk>

To: submit@bugs.debian.org

Subject: interactive client dies on ill-timed SIGWINCH

Date: Tue, 17 Oct 2006 14:30:15 +0100

Package: openssh-client
Version: 1:4.3p2-3

I often ask my window manager to bring up `xterm -e ssh somehost'.  I
have the wm configured to allow me to interactively place resize the
window.  Sometimes, when I do this, the xterm and ssh vanish.  Process
accounting shows ssh dying with exit status 255.

I've spoken to other users and they report that this happens to them
sometimes too.

I suspect that the SIGWINCH arrives at a time when ssh is buggily
unable to cope with EINTR.

I realise that this report isn't particularly informative.  Please let
me know what additional tests/diagnostics you'd like me to do.
Unfortunately I can't reproduce the symptoms on demand; it happens to
me spontaneously about once every few weeks.  Any instrumentation
you want me to do would have to be reasonable to do for all of my ssh
sessions until the bug recurs, and would have to not affect the
timings significantly.

Ian.

Message #10 received at 393704@bugs.debian.org (full text, mbox, reply):

From: Colin Watson <cjwatson@debian.org>

To: Ian Jackson <ian@davenant.greenend.org.uk>, 393704@bugs.debian.org

Subject: Re: Bug#393704: interactive client dies on ill-timed SIGWINCH

Date: Tue, 17 Oct 2006 15:28:08 +0100

On Tue, Oct 17, 2006 at 02:30:15PM +0100, Ian Jackson wrote:
> I often ask my window manager to bring up `xterm -e ssh somehost'.  I
> have the wm configured to allow me to interactively place resize the
> window.  Sometimes, when I do this, the xterm and ssh vanish.  Process
> accounting shows ssh dying with exit status 255.
> 
> I've spoken to other users and they report that this happens to them
> sometimes too.
> 
> I suspect that the SIGWINCH arrives at a time when ssh is buggily
> unable to cope with EINTR.

This would not especially surprise me.

> I realise that this report isn't particularly informative.  Please let
> me know what additional tests/diagnostics you'd like me to do.
> Unfortunately I can't reproduce the symptoms on demand; it happens to
> me spontaneously about once every few weeks.  Any instrumentation
> you want me to do would have to be reasonable to do for all of my ssh
> sessions until the bug recurs, and would have to not affect the
> timings significantly.

Could you redirect ssh's stderr to a file (if it isn't already going to
~/.xsession-errors or similar) and find out if it emits any error
messages before exiting? The general style of OpenSSH code is such that
I would expect there to be an error message to identify the failing
system call.

Thanks,

-- 
Colin Watson                                       [cjwatson@debian.org]

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