ssh: limits on authorized_keys2 (fwd)

[Arnim Littek]

Damien wrote:
> Could you redo your traces with "-v -v -v" set? Best send the report to
> openssh-unix-dev at mindrot.org so it isn't just myself looking at it.

Attached are a number of log files from a problem I'm seeing with
DSA/authorized_keys2 when operating ssh strictly with Protocol
2.  Damien has not been able to reproduce it with his RSA setup.

When my server has more than X entries in authorized_keys2, the ssh
connection is rejected, whereas when that pubkey is in the first X,
the connection works fine.  All that I am doing in between is
shuffling the order of the pubkeys.  On one machine, X=2, on the
machine I did this logging on, X=3.

There's a nice, clear error message in the server's auth.log:

Dec 19 11:10:26 cabrio sshd[23206]: fatal: buffer_get: trying to get
more bytes 128 than in buffer 91

which has to be a useful clue.  Files in the attached tarball:

auth.log-cabrio  - server /var/log/auth.log
log_auth2cabrio.1stposn - failed ssh login, logged via: 
           ssh -v -v -v -4 cabrio 2> log_auth2cabrio.1stposn  
log_auth2cabrio.4thposn - successful ssh login, same command line,
           except for logfilename and ordering of pubkeys in
             cabrio:/home/arnim/.ssh/authorized_keys2
ssh_config-fox - client /etc/ssh/ssh_config
sshd_config-cabrio - server /etc/ssh/sshd_config

Note that this example is done between a RedHat client and a Debian
server, but I have seen the same fault with an OBSD 3.0 server and
other clients.

I hope this is sufficient to motivate someone to have a poke at the
buffer_get code...  Any other information on the circumstance is
available upon request.

Arnim.
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