[Dovecot] Assertion error in Dovecot 2.2.6

[Mark Sapiro]

Background.

A while back I upgraded my phone to one currently using Android 4.1.2
and K9 mail 4.409. This phone/MUA combination seems at times to go crazy
making IMAP connections.

At first, I had mail_max_userip_connections = 30 (my largest imap
account has 19 folders). The issue I had at that time was multiple
errors like

Oct 14 17:45:16 sbh16 dovecot: imap-login: Maximum number of connections
from user+IP exceeded (mail_max_userip_connections=30): user=<xxx>,
method=PLAIN, rip=xx.xx.xx.xx, lip=xx.xx.xx.xx, TLS,
session=<c63x5bzowQBi0uQR>

I then set mail_max_userip_connections = 50

This greatly reduced but didn't completely eliminate these messages, but
then I would see multiple

Oct 31 16:13:40 sbh16 dovecot: master: Warning: service(imap-login):
process_limit (100) reached, client connections are being dropped

and

Oct 31 16:13:40 sbh16 dovecot: imap-login: Disconnected: Connection
queue full (no auth attempts in 4 secs): user=<>, rip=xx.xx.xx.xx,
lip=xx.xx.xx.xx, TLS handshaking, session=<s26xmRHqVQBi0uQR>

followed finally by

Oct 31 16:13:40 sbh16 dovecot: imap-login: Panic: file client-common.c:
line 190 (client_destroy): assertion failed: (!client->authenticating)

Oct 31 16:13:40 sbh16 dovecot: auth: Warning: auth client 19669
disconnected with 1 pending requests: EOF

Oct 31 16:13:40 sbh16 dovecot: imap-login: Fatal: master:
service(imap-login): child 19669 killed with signal 6 (core not dumped -
add -D parameter to service imap-login { executable }

I then set default_process_limit = 200, and things seem to have settled
down, but I thought the panic should be reported.

Possibly this is relevant - the above only seem to occur when the phone
is connecting via wifi and possibly only when the phone has just
switched from the phone data network to wifi.

Current doveconf -n
# 2.2.6: /usr/local/etc/dovecot/dovecot.conf
# OS: Linux 2.6.18-8.1.14.el5 i686 CentOS release 5 (Final)
auth_mechanisms = plain apop login
auth_worker_max_count = 5
default_process_limit = 200
mail_location = mbox:~/Mail:INBOX=/var/spool/mail/%u
mail_privileged_group = mail
mbox_write_locks = fcntl dotlock
namespace inbox {
  inbox = yes
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix =
}
passdb {
  args = /usr/local/etc/dovecot.passwd
  driver = passwd-file
}
passdb {
  driver = pam
}
protocols = imap pop3
service auth {
  unix_listener /var/spool/postfix/private/auth {
    mode = 0666
  }
}
ssl_cert = </etc/httpd/conf/ssl/combined.crt
ssl_key = </etc/httpd/conf/ssl/www.grizz.org.key
userdb {
  driver = passwd
}
protocol imap {
  mail_max_userip_connections = 50
}

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan