imap-login segfaulting on 2.3.1

[Grant Keller]

Hello,

I have a new director ring I am setting up on centos 7 with dovecot
2.3.1. I haven't been able to replecate this in testing, but as soon as
I start pushing production traffic to the new ring I see dozens of these  in the
logs:
Apr 18 00:34:00 d.director.imapd.sonic.net kernel: imap-login[163107]: segfault at 10 ip 00007ff625698dd5sp 00007ffe4b77bb28 error 4 in libdovecot.so.0.0.0[7ff6255bf000+16e000]

My config:
# 2.3.1 (c5a5c0c82): /etc/dovecot/dovecot.conf
# OS: Linux 3.10.0-693.21.1.el7.x86_64 x86_64 CentOS Linux release 7.4.1708 (Core)
# Hostname: c.director.imapd.sonic.net
auth_master_user_separator = *
auth_username_format = %Ln
auth_verbose = yes
default_client_limit = 20000
director_mail_servers = 64.142.111.75 64.142.111.43 64.142.111.76 64.142.111.39 64.142.111.81
director_servers = c.director.imapd.sonic.net d.director.imapd.sonic.net
disable_plaintext_auth = no
doveadm_port = 1842
login_trusted_networks = 64.142.18.0/24 64.142.105.2 64.142.111.67 64.142.111.36  64.142.105.3 64.142.111.35 64.142.111.68
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 = /etc/dovecot/master-users
  driver = passwd-file
  master = yes
  pass = yes
}
passdb {
  args = proxy=y nopassword=y
  driver = static
}
service anvil {
  client_limit = 40103
}
service auth {
  client_limit = 41704
}
service director {
  fifo_listener login/proxy-notify {
    mode = 0666
  }
  inet_listener {
    port = 9321
  }
  unix_listener login/director {
    mode = 0666
  }
}
service imap-login {
  executable = imap-login director
  process_limit = 20000
  process_min_avail = 32
}
service imap {
  process_limit = 20480
}
service ipc {
  unix_listener ipc {
    user = dovecot
  }
}
service pop3-login {
  executable = pop3-login director
  process_limit = 20000
  process_min_avail = 32
}
ssl_cert = </etc/dovecot/ssl/imap.sonic.net.pem
ssl_cipher_list = ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA
ssl_dh =  # hidden, use -P to show it
ssl_key =  # hidden, use -P to show it
syslog_facility = local0
protocol imap {
  imap_max_line_length = 128 k
  ssl_cert = </etc/dovecot/ssl/imap.sonic.net.pem
  ssl_key =  # hidden, use -P to show it
}
protocol pop3 {
  ssl_cert = </etc/dovecot/ssl/pop.sonic.net.pem
  ssl_key =  # hidden, use -P to show it
}

backtrace:
                Stack trace of thread 56084:
                #0  0x00007fe529be2dd5 i_stream_get_root_io (libdovecot.so.0)
                #1  0x00007fe529be2e39 i_stream_set_input_pending (libdovecot.so.0)
                #2  0x00007fe527415a59 openssl_iostream_bio_sync (libssl_iostream_openssl.so)
                #3  0x00007fe527415c2a openssl_iostream_more (libssl_iostream_openssl.so)
                #4  0x00007fe527415c6b openssl_iostream_destroy (libssl_iostream_openssl.so)
                #5  0x00007fe529e8be72 client_unref (libdovecot-login.so.0)
                #6  0x00007fe529e90441 login_proxy_free_full (libdovecot-login.so.0)
                #7  0x00007fe529e90e07 login_proxy_finished (libdovecot-login.so.0)
                #8  0x00007fe529becfb5 io_loop_call_io (libdovecot.so.0)
                #9  0x00007fe529bee89f io_loop_handler_run_internal (libdovecot.so.0)
                #10 0x00007fe529bed0b2 io_loop_handler_run (libdovecot.so.0)
                #11 0x00007fe529bed2d8 io_loop_run (libdovecot.so.0)
                #12 0x00007fe529b69673 master_service_run (libdovecot.so.0)
                #13 0x00007fe529e93532 login_binary_run (libdovecot-login.so.0)
                #14 0x00007fe529767c05 __libc_start_main (libc.so.6)
                #15 0x00005567b256050a _start (imap-login)



Grant Keller
System Operations
grant.keller at sonic.com