Bug#837123: [anna] segfault in wheezy installer
On 2016-09-10 11:30, Vincent McIntyre wrote:
> On Fri, Sep 09, 2016 at 03:59:17PM +0200, Aurelien Jarno wrote:
> >
> > I don't talk about the software running on your DNS servers, but
> > rather how they behave when they get queried. It might depends on
> > many other things, like if your network has IPv6 or not.
> >
> > Note that's only one explanation, not sure it's the right one, but
> > given I am unable to reproduce the issue, it's the only one that
> > come to my mind.
>
> Thank you for explaining. I am struggling with this idea since AFAIK
> the DNS servers have not been changed in the last six months or more
> so I can think of no reason for the behaviour to have changed.
Thanks for the details, that's an important information.
> That history is what makes me think something must have changed in
> the installer around the time of the last point release (May).
> But from what you say that isn't the case.
The installer did change, and has been built against a new libc which
includes changes to the resolver, fixing security issues. I am not aware
of any issue introduced by these patches (this libc is used on regular
systems, not only in debian-installer), except #816669 which involves
IPv6 and has different symptoms.
> You've given me a few things to try out
> - tell DHCP to supply different DNS servers (running bind)
> - make sure all ipv6 related options are disabled
> and no ipv6 DNS entries exist for the target host
> - make sure all ipv6 related options are enabled
> and valid ipv6 DNS entries exist for the target host
>
> Also I can try installing oldstable with the jessie installer.
>
> If all of that makes no difference, what would be the next step?
What would be interesting would be to try to reproduce the issue in
qemu or virtualbox, with as many things as possible close to your
system.
Also you might want to use the console (alt+f2) to run wget by hand and
see if the issue happen with all hosts or only some of them.
> I assume I'd have to build a debug version of the installer
> and try to get a backtrace?
I don't know if it's really something doable, especially the wheezy
installer use a shared library reduction system to strip some symbols
from the shared libraries.
> My concern is there's a segfault still lurking in the stretch
> version. If we can squash it here that fix could be forward-ported.
This is very unlikely, as both debian-installer and glibc are quite
different in stretch and do not use the shared library reduction
anymore.
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net
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