[Bug 1056756] [NEW] sshd: preauth child terminated by signal 11

[wiz]

Public bug reported:

Can't connect to a local installation of openssh-server.

ssh localhost fails with "Broken pipe", here's the tail of ssh -vv:

...
debug1: Enabling compression at level 6.
debug1: Authentication succeeded (publickey).
Authenticated to localhost ([127.0.0.1]:22).
debug1: channel 0: new [client-session]
debug2: channel 0: send open
debug1: Requesting no-more-sessions at openssh.com
debug1: Entering interactive session.
Write failed: Broken pipe

Those lines are appearing in auth.log:

Sep 26 14:09:10 natali sshd[6076]: Accepted publickey for wiz from 127.0.0.1 port 48624 ssh2
Sep 26 14:09:10 natali sshd[6076]: fatal: privsep_preauth: preauth child terminated by signal 11

Also, any ssh invocation (even -h) ends with "Segmentation fault":

usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]
           [-D [bind_address:]port] [-e escape_char] [-F configfile]
           [-I pkcs11] [-i identity_file]
           [-L [bind_address:]port:host:hostport]
           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]
           [-R [bind_address:]port:host:hostport] [-S ctl_path]
           [-W host:port] [-w local_tun[:remote_tun]]
           [user@]hostname [command]
Segmentation fault

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: openssh-server 1:6.0p1-3ubuntu1
ProcVersionSignature: Ubuntu 3.5.0-15.22-generic 3.5.4
Uname: Linux 3.5.0-15-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.5.2-0ubuntu4
Architecture: amd64
Date: Wed Sep 26 14:01:24 2012
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120724.2)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SSHDConfig: Error: command ['pkexec', '/usr/sbin/sshd', '-T'] failed with exit code -11:
SourcePackage: openssh
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: openssh (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug quantal running-unity

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https://bugs.launchpad.net/bugs/1056756

Title:
  sshd: preauth child terminated by signal 11

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