OpenSSH 4.0p1 segfaults on keyboard-interactive login

[Darren Tucker]

Andreas M. Kirchwitz wrote:
> Hi folks,
> 
> I've compiled the new OpenSSH 4.0p1 on my Linux box running
> Fedora Core 2 (kernel 2.6.10) the same way as I did with 3.9p1
> and all previous versions.
> 
> Key-based login works fine, but if I login from a host that
> require me to enter my login password (keyboard-interactive),
> then the sshd child process segfaults.
> 
> Don't know if this is specific to my system or to Linux in
> general. On Solaris 9 SPARC, everything works fine.

I believe this is something relating to glibc and nameservice lookups in 
a chroot.  It looks like libc tries to dynamically load some nameservice 
modules then blows up when it fails (because they don't exist in the 
chroot).  If you can get a gdb backtrace of it I think you'll find it's 
inside libc when it dies.

Try
  - "UseDNS no" in sshd_config.

  - cp -a /lib /var/empty (or wherever your sshd chroot is).  You won't 
need all of the libraries, though.

  - create an /etc/nsswitch.conf inside the chroot that has only "hosts: 
files".

-- 
Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
     Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.