dovecot: imap-login: Panic: Trying to allocate 0 bytes

[Ron Garret]

My ISP had a hard drive crash.  After the dust settled, my dovecot installation started failing with the following error every time a client tries to connect:

dovecot: imap-login: Panic: Trying to allocate 0 bytes

My installation has otherwise been stable and rock-solid for years.  Both I and the techs at my ISP are stumped.  Any advice on how to debug this would be greatly appreciated.

Vital info:

[ron at vm1:/etc/dovecot]$ /usr/sbin/dovecot -n
# 1.2.15: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-5-amd64 x86_64 Debian 6.0.10 
log_timestamp: %Y-%m-%d %H:%M:%S 
ssl_ca_file: /etc/ssl/local-certs/startssl.ca.pem
ssl_cert_file: /etc/ssl/local-certs/...
ssl_key_file: /etc/ssl/local-keys/...
login_dir: /var/run/dovecot/login
login_executable: /usr/lib/dovecot/imap-login
first_valid_uid: 100
mail_privileged_group: mail
mbox_write_locks: fcntl dotlock
auth default:
  user: postfix
  passdb:
    driver: sql
    args: /etc/dovecot/dovecot-sql.conf
  userdb:
    driver: prefetch
  socket:
    type: listen
    client:
      path: /var/spool/postfix/private/auth
      mode: 432
      user: postfix
      group: postfix

I have checked the MySQL configuration and everything seems to be OK there.  In fact, I’ve checked everything that I know how to check, and everything seems to be OK.  And yet it is not working.

Many thanks,
rg