dovecot - Nov 2019 - Panic: file smtp-client-connection.c: line 1142 (smtp_client_connection_established)

I'm using dovecot in a multi server setup. Two directors forward pop3, imap
and smtp to  backend dovecots with their central storage on NFS.
Yesterday I stumbled upon these log lines:

2019-11-18 20:17:51 lmtp(17274): Info: Connect from 172.22.1.6
2019-11-18 20:17:51 lmtp(17274): Panic: file smtp-client-connection.c: line 1142
(smtp_client_connection_established): assertion failed:
(!conn->connect_succeeded)
2019-11-18 20:17:51 lmtp(17274): Fatal: master: service(lmtp): child 17274
killed with signal 6 (core not dumped -
https://dovecot.org/bugreport.html#coredumps - set /proc/sys/fs/suid_dumpable to
2)

Is a core dump required to find the source of that error?

Thanks for any help!


$ doveconf -n
# 2.3.4.1 (f79e8e7e4): /etc/dovecot/dovecot.conf
# OS: Linux 4.9.0-8-amd64 x86_64
# Hostname: m03.company.com
auth_cache_negative_ttl = 65 secs
auth_cache_ttl = 3 mins
auth_cache_verify_password_with_worker = yes
auth_mechanisms = plain login
auth_verbose = yes
debug_log_path = /dev/stdout
default_client_limit = 10400
default_process_limit = 1024
default_vsz_limit = 1 G
deliver_log_format = msgid=%m: %s %{session_time} %$
director_mail_servers = 10.10.10.2 10.10.10.3
director_servers = 10.10.1.2 10.10.1.3
imap_id_log = *
imap_max_line_length = 2 M
import_environment = TZ CORE_OUTOFMEM CORE_ERROR
info_log_path = /dev/stdout
instance_name = dovecot_director
listen = 10.10.1.3,::
lmtp_proxy = yes
log_path = /dev/stderr
log_timestamp = "%Y-%m-%d %H:%M:%S "
login_log_format_elements = user=<%u> method=%m rip=%r lip=%l mpid=%e %c
%k session=<%{session}>
mail_max_userip_connections = 250
passdb {
  args = /etc/dovecot/sql/dovecot-dict-sql-passdb.conf
  driver = sql
  result_failure = return-fail
  result_internalfail = return-fail
  result_success = continue-ok
}
passdb {
  args = proxy=y starttls=any-cert master=director at m03.company.com
pass=#hidden_use-P_to_show# nopassword=y
  driver = static
  skip = unauthenticated
}
pop3_logout_format = top=%t/%p, retr=%r/%b, del=%d/%m, size=%s, uidl=%u
protocols = imap lmtp pop3
service auth-worker {
  user = $default_internal_user
}
service director {
  fifo_listener login/proxy-notify {
    mode = 0600
    user = $default_login_user
  }
  inet_listener {
    port = 9090
  }
  unix_listener director-userdb {
    mode = 0600
    user = vmail
  }
  unix_listener login/director {
    mode = 0666
  }
}
service imap-login {
  executable = imap-login director
  process_min_avail = 2
  vsz_limit = 1 G
}
service lmtp {
  inet_listener lmtp {
    port = 24
  }
  process_min_avail = 2
  unix_listener lmtp {
    mode = 00
  }
  user = vmail
  vsz_limit = 1 G
}
service log {
  user = dovenull
}
service pop3-login {
  executable = pop3-login director
  process_min_avail = 2
  vsz_limit = 1 G
}
service pop3 {
  user = vmail
}
ssl_cert = </etc/ssl/mail/cert.pem
ssl_client_ca_dir = /etc/ssl/certs/
ssl_dh = # hidden, use -P to show it
ssl_key = # hidden, use -P to show it
ssl_prefer_server_ciphers = yes
submission_host = postfix:588
protocol lmtp {
  auth_socket_path = director-userdb
}
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On 19/11/2019 13:25, Dirk via dovecot wrote:
> I'm using dovecot in a multi server setup. Two directors forward pop3, 
> imap and smtp to ?backend dovecots with their central storage on NFS.
> Yesterday I stumbled upon these log lines:
>
> 2019-11-18 20:17:51 lmtp(17274): Info: Connect from 172.22.1.6
> 2019-11-18 20:17:51 lmtp(17274): Panic: file smtp-client-connection.c: 
> line 1142 (smtp_client_connection_established): assertion failed: 
> (!conn->connect_succeeded)
> 2019-11-18 20:17:51 lmtp(17274): Fatal: master: service(lmtp): child 
> 17274 killed with signal 6 (core not dumped - 
> https://dovecot.org/bugreport.html#coredumps - set 
> /proc/sys/fs/suid_dumpable to 2)
>
> Is a core dump required to find the source of that error?
>
This bug is known (DOV-3600), fixed and currently scheduled for release 
in 2.3.10.

Regards,

Stephan.
> Thanks for any help!
>
>
> $ doveconf -n
> # 2.3.4.1 (f79e8e7e4): /etc/dovecot/dovecot.conf
> # OS: Linux 4.9.0-8-amd64 x86_64
> # Hostname: m03.company.com <http://m03.company.com>
> auth_cache_negative_ttl = 65 secs
> auth_cache_ttl = 3 mins
> auth_cache_verify_password_with_worker = yes
> auth_mechanisms = plain login
> auth_verbose = yes
> debug_log_path = /dev/stdout
> default_client_limit = 10400
> default_process_limit = 1024
> default_vsz_limit = 1 G
> deliver_log_format = msgid=%m: %s %{session_time} %$
> director_mail_servers = 10.10.10.2 10.10.10.3
> director_servers = 10.10.1.2 10.10.1.3
> imap_id_log = *
> imap_max_line_length = 2 M
> import_environment = TZ CORE_OUTOFMEM CORE_ERROR
> info_log_path = /dev/stdout
> instance_name = dovecot_director
> listen = 10.10.1.3,::
> lmtp_proxy = yes
> log_path = /dev/stderr
> log_timestamp = "%Y-%m-%d %H:%M:%S "
> login_log_format_elements = user=<%u> method=%m rip=%r lip=%l mpid=%e
> %c %k session=<%{session}>
> mail_max_userip_connections = 250
> passdb {
> ? args = /etc/dovecot/sql/dovecot-dict-sql-passdb.conf
> ? driver = sql
> ? result_failure = return-fail
> ? result_internalfail = return-fail
> ? result_success = continue-ok
> }
> passdb {
> ? args = proxy=y starttls=any-cert master=director at m03.company.com 
> <mailto:master=director at m03.company.com>
pass=#hidden_use-P_to_show#
> nopassword=y
> ? driver = static
> ? skip = unauthenticated
> }
> pop3_logout_format = top=%t/%p, retr=%r/%b, del=%d/%m, size=%s, uidl=%u
> protocols = imap lmtp pop3
> service auth-worker {
> ? user = $default_internal_user
> }
> service director {
> ? fifo_listener login/proxy-notify {
> ? ? mode = 0600
> ? ? user = $default_login_user
> ? }
> ? inet_listener {
> ? ? port = 9090
> ? }
> ? unix_listener director-userdb {
> ? ? mode = 0600
> ? ? user = vmail
> ? }
> ? unix_listener login/director {
> ? ? mode = 0666
> ? }
> }
> service imap-login {
> ? executable = imap-login director
> ? process_min_avail = 2
> ? vsz_limit = 1 G
> }
> service lmtp {
> ? inet_listener lmtp {
> ? ? port = 24
> ? }
> ? process_min_avail = 2
> ? unix_listener lmtp {
> ? ? mode = 00
> ? }
> ? user = vmail
> ? vsz_limit = 1 G
> }
> service log {
> ? user = dovenull
> }
> service pop3-login {
> ? executable = pop3-login director
> ? process_min_avail = 2
> ? vsz_limit = 1 G
> }
> service pop3 {
> ? user = vmail
> }
> ssl_cert = </etc/ssl/mail/cert.pem
> ssl_client_ca_dir = /etc/ssl/certs/
> ssl_dh = # hidden, use -P to show it
> ssl_key = # hidden, use -P to show it
> ssl_prefer_server_ciphers = yes
> submission_host = postfix:588
> protocol lmtp {
> ? auth_socket_path = director-userdb
> }