Re: cygwin bash-4.1.9-2

Re: cygwin bash-4.1.9-2

[Kimbo Mundy]

On Wed, 02 Feb 2011 12:47:00 -0700, Eric Blake wrote:
> On 02/02/2011 09:38 AM, Philipp Wiendl wrote:
> > Hello,
> >
> > today i installed cygwin v1.7 with the new v4 bash package.
> > I tried to run ssh-host-config and got following error:
> >
> > $ ssh-host-config -y
> > *** Query: Overwrite existing /etc/ssh_config file? (yes/no) yes
> > *** Info: Creating default /etc/ssh_config file
> > Segmentation fault (core dumped)
> >
> > After a fallback to v3 bash package the setup for the sshd works fine.
> > Maybe you can reproduce this issue and fix it.
>
> I have not seen that issue, and you're the first to report it, but I'll
> see if I can reproduce it.  Meanwhile, could you run:
>
> bash -vx ssh-host-config -y
>
> to pinpoint where it crashes?

I just hit this as well.  I had to use --debug, instead of bash -xv,
in order to get tracing turned on inside
/usr/share/csih/cygwin-service-installation-helper.sh.  It appears the
crash happens as csih_install_config is returning:

$ ssh-host-config --debug -y
...
*** Info: Creating default /etc/ssh_config file
+ set -x
++ csih_stacktrace 'returning with' 0
++ set +x
*** STACKTRACE: main[540]->csih_install_config[1519]->csih_inform[637]
returning with 0
+ cp /etc/defaults//etc/ssh_config /etc/ssh_config
+ return
++ csih_stacktrace 'returning with' 0
++ set +x
*** STACKTRACE: main[540]->csih_install_config[1522] returning with 0
Segmentation fault (core dumped)

I hope this helps.  In the meantime, it's back to v3.

Thanks, Kimbo

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Re: cygwin bash-4.1.9-2

[Eric Blake]

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On 02/08/2011 12:15 PM, Kimbo Mundy wrote:
>> I have not seen that issue, and you're the first to report it, but I'll
>> see if I can reproduce it.

I was able to reproduce this, but not on my machine (thanks Corinna for
getting me set up); and the odd thing was that the problem disappears
when compiled with -O1 on execute_cmd.c.  Bash is probably doing
something undefined, that happens to work at low optimization but falls
flat at high optimization; in particular, it is violating rules of
setjmp() by modifying local variables not marked volatile in between
setjmp() and longjmp().  However, when I silenced that gcc warning, the
crash still persisted at -O2, so I haven't solved root cause yet.

At any rate, if I can't solve root cause shortly, I'll at least release
bash-4.1.9-3 with execute_cmd.c compiled at -O1 to avoid the problem,
while I continue my investigations.

> I just hit this as well.  I had to use --debug, instead of bash -xv,
> in order to get tracing turned on inside
> /usr/share/csih/cygwin-service-installation-helper.sh.  It appears the
> crash happens as csih_install_config is returning:

The crash is happening when csih_install_config is executing a return
trap.  It could be that not too many people do trap ... RETURN in bash
scripts, which is why cygwin is hitting this problem, even though it
appears to be a bug in upstream bash (at least, it's more likely that
bash is doing something wrong than it is that gcc 4.3.4 is miscompiling
bash).

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org


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Re: cygwin bash-4.1.9-2

[Eric Blake]

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[adding the list: http://cygwin.com/acronyms/#PPIOSPE]

On 02/02/2011 09:38 AM, Philipp Wiendl wrote:
> Hello,
> 
> today i installed cygwin v1.7 with the new v4 bash package.
> I tried to run ssh-host-config and got following error:
> 
> $ ssh-host-config -y
> *** Query: Overwrite existing /etc/ssh_config file? (yes/no) yes
> *** Info: Creating default /etc/ssh_config file
> Segmentation fault (core dumped)
> 
> After a fallback to v3 bash package the setup for the sshd works fine.
> Maybe you can reproduce this issue and fix it.

I have not seen that issue, and you're the first to report it, but I'll
see if I can reproduce it.  Meanwhile, could you run:

bash -vx ssh-host-config -y

to pinpoint where it crashes?

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org


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