Panic: data stack: Out of memory when allocating bytes

[Thomas Robers]

Hello,

I'm using Dovecot 2.3 and sometimes i get this:

--- snip ---
Jan 23 14:23:13 mail dovecot: 
imap(bob at tutech.de)<4880><PDqibHFjMvrAqG1n>: Panic: data stack: Out of 
memory when allocating 134217768 bytes
Jan 23 14:23:13 mail dovecot: 
imap(bob at tutech.de)<4880><PDqibHFjMvrAqG1n>: Fatal: master: 
service(imap): child 4880 killed with signal 6 (core dumped)
--- snip ---

The gdb backtrace is:

--- snip ---
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-92.el6)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/libexec/dovecot/imap...(no debugging symbols 
found)...done.
Attaching to program: /usr/libexec/dovecot/imap, process 4880
ptrace: Kein passender Prozess gefunden.
[New Thread 4880]
Reading symbols from /usr/lib64/dovecot/libdovecot-storage.so.0...(no 
debugging symbols found)...done.
Loaded symbols for /usr/lib64/dovecot/libdovecot-storage.so.0
Reading symbols from /usr/lib64/dovecot/libdovecot.so.0...(no debugging 
symbols found)...done.
Loaded symbols for /usr/lib64/dovecot/libdovecot.so.0
Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/librt.so.1...(no debugging symbols 
found)...done.
Loaded symbols for /lib64/librt.so.1
Reading symbols from /lib64/libdl.so.2...(no debugging symbols 
found)...done.
Loaded symbols for /lib64/libdl.so.2
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols 
found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /lib64/libpthread.so.0...(no debugging symbols 
found)...done.
[Thread debugging using libthread_db enabled]
Loaded symbols for /lib64/libpthread.so.0
Reading symbols from /usr/lib64/dovecot/lib01_acl_plugin.so...(no 
debugging symbols found)...done.
Loaded symbols for /usr/lib64/dovecot/lib01_acl_plugin.so
Reading symbols from /usr/lib64/dovecot/lib02_imap_acl_plugin.so...(no 
debugging symbols found)...done.
Loaded symbols for /usr/lib64/dovecot/lib02_imap_acl_plugin.so
Reading symbols from /usr/lib64/dovecot/lib15_notify_plugin.so...(no 
debugging symbols found)...done.
Loaded symbols for /usr/lib64/dovecot/lib15_notify_plugin.so
Reading symbols from /usr/lib64/dovecot/lib20_mail_log_plugin.so...(no 
debugging symbols found)...done.
Loaded symbols for /usr/lib64/dovecot/lib20_mail_log_plugin.so
Reading symbols from /usr/lib64/dovecot/lib20_zlib_plugin.so...(no 
debugging symbols found)...done.
Loaded symbols for /usr/lib64/dovecot/lib20_zlib_plugin.so
Reading symbols from /lib64/libz.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib64/libz.so.1
Reading symbols from /lib64/libbz2.so.1...(no debugging symbols 
found)...done.
Loaded symbols for /lib64/libbz2.so.1
Reading symbols from /usr/lib64/dovecot/lib30_imap_zlib_plugin.so...(no 
debugging symbols found)...done.
Loaded symbols for /usr/lib64/dovecot/lib30_imap_zlib_plugin.so
Core was generated by `dovecot/imap'.
Program terminated with signal 6, Aborted.
#0  0x00007f73f1386495 in raise () from /lib64/libc.so.6
--- snip ---

I searched for that error message but only found some entries regarding
older dovecot versions and setting "mail_process_size" but i couldn't
find anything regarding Dovecot Version 2.3. Maybe it's something that 
is fixed already but if so i can't find it. Or is this a configuration 
issue or a bug?

Here my Dovecot configuration:

--- snip ---
# 2.3.0 (c8b89eb): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.0.1 (d33dca20)
# OS: Linux 2.6.32-696.3.1.el6.x86_64 x86_64 CentOS release 6.9 (Final) ext4
auth_debug = yes
auth_debug_passwords = yes
auth_master_user_separator = *
auth_mechanisms = plain login
auth_verbose = yes
disable_plaintext_auth = no
doveadm_password =  # hidden, use -P to show it
doveadm_port = 12345
imap_max_line_length = 2 M
mail_debug = yes
mail_location = maildir:/export/home/imap/%Lu/Maildir
mail_plugins = acl zlib mail_log notify
mailbox_idle_check_interval = 10 secs
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope 
encoded-character vacation subaddress comparator-i;ascii-numeric 
relational regex imap4flags copy include variables body enotify 
environment mailbox date index ihave duplicate mime foreverypart extracttext
namespace {
   hidden = no
   ignore_on_failure = no
   inbox = no
   list = children
   location = maildir:%%h/Maildir:INDEXPVT=%h/shared/%%u
   prefix = shared/%%u/
   separator = /
   subscriptions = yes
   type = shared
}
namespace inbox {
   hidden = no
   inbox = yes
   list = 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 = INBOX/
   separator = /
   type = private
}
passdb {
   args = /etc/dovecot/master-users
   driver = passwd-file
   master = yes
}
passdb {
   args = /etc/dovecot/dovecot-ldap.conf.ext
   driver = ldap
}
plugin {
   acl = vfile:/etc/dovecot/global-acls:cache_secs=300
   acl_shared_dict = file:/export/home/shared-db/shared-mailboxes
   mail_log_events = append delete undelete expunge copy mailbox_delete 
mailbox_rename flag_change
   mail_log_fields = uid box msgid size from flags
   mail_replica = tcp:mail2.tutech.de
   sieve = ~/.dovecot.sieve
   sieve_dir = ~/sieve
   sieve_global = /var/lib/dovecot/sieve/global/
   sieve_user_log = ~/.dovecot.sieve.log
   zlib_save = gz
   zlib_save_level = 6
}
protocols = imap pop3 lmtp sieve sieve
service aggregator {
   fifo_listener replication-notify-fifo {
     mode = 0666
     user = vmail
   }
   unix_listener replication-notify {
     mode = 0666
     user = vmail
   }
}
service auth {
   unix_listener /var/spool/postfix/private/auth {
     mode = 0666
   }
   unix_listener auth-userdb {
     group = vmail
     mode = 0660
     user = vmail
   }
}
service config {
   unix_listener config {
     user = vmail
   }
}
service doveadm {
   inet_listener {
     port = 12345
   }
   user = vmail
}
service imap-login {
   inet_listener imaps {
     port = 993
     ssl = yes
   }
   process_limit = 500
   process_min_avail = 20
}
service imap {
   executable = imap
}
service lmtp {
   inet_listener lmtp {
     address = 127.0.0.1
     port = 24
   }
}
service managesieve-login {
   inet_listener sieve {
     port = 4190
   }
   inet_listener sieve_deprecated {
     port = 2000
   }
}
service pop3-login {
   inet_listener pop3s {
     port = 995
     ssl = yes
   }
}
service pop3 {
   executable = pop3
}
service replicator {
   unix_listener replicator-doveadm {
     mode = 0666
   }
}
ssl = required
ssl_cert = </etc/pki/dovecot/certs/mail.tutech.de.crt_chain
ssl_cipher_list = ALL:!LOW:!SSLv2:!EXP:!aNULL:!EXPORT
ssl_dh =  # hidden, use -P to show it
ssl_key =  # hidden, use -P to show it
syslog_facility = local6
userdb {
   args = /etc/dovecot/dovecot-ldap-userdb.conf.ext
   driver = ldap
}
protocol lmtp {
   mail_plugins = acl zlib mail_log notify sieve
}
protocol imap {
   mail_max_userip_connections = 100
   mail_plugins = acl zlib mail_log notify imap_zlib imap_acl
   rawlog_dir = /tmp/rawlog/%u
}
--- snip ---


Thanks for the help!

Kind regards
Thomas