Fatal error with IMAP MOVE from a shared mailbox to Trash folder

Tue Dec 27 16:35:24 UTC 2016

Hello everyone.
I have a problem using Dovecot 2.2.26 with ACL plugin and deleting e-mails
from a shared mailbox.

My user doesn't have the "expunge" permission on the shared mailbox, but it
has the "write-deleted" permission. So, when I delete a message from the
shared mailbox using a client that implements the IMAP MOVE command, it
tries to move the message to my Trash folder. Then the server closes the
connection to the client (process aborted) and I get three lines in the log
file with a backtrace and "Fatal" error. In this case the message doesn't
get copied or moved from the shared folder and the client complaints. I
found the same thing happens whenever I try to move anything between
folders of the shared mailbox itself, while logged in with my user. I can
move messages inside my own mailbox just fine.

If I try the same operation from a client that uses the IMAP COPY + DELETE
commands, no errors are logged and the outcome is as expected: the message
gets copied from the shared folder to my Trash and gets the flag "\Deleted"
set on the shared folder.

My setup is as follows:

  Dovecot: 2.2.26.0
  OS: Ubuntu 16.04.1 LTS
  CPU architecture: x86_64
  Filesystem: ext4

The relevant lines from mail.err log:

Dec 27 15:21:18 dovecot dovecot: imap(danielebarresi): Panic: file
mail-storage.c: line 2143 (mailbox_save_context_reset): assertion failed:
(ctx->copying_via_save)
Dec 27 15:21:18 dovecot dovecot: imap(danielebarresi): Error: Raw
backtrace: /usr/lib/dovecot/libdovecot.so.0(+0x9438e) [0x7fbcd478538e] ->
/usr/lib/dovecot/libdovecot.so.0(+0x9447c) [0x7fbcd478547c] ->
/usr/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7fbcd471ea4e] ->
/usr/lib/dovecot/libdovecot-storage.so.0(+0x41b78) [0x7fbcd4a50b78] ->
/usr/lib/dovecot/libdovecot-storage.so.0(mailbox_save_cancel+0x73)
[0x7fbcd4a53d73] -> /usr/lib/dovecot/modules/lib01_acl_plugin.so(+0xe142)
[0x7fbcd3f1d142] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0x4516d)
[0x7fbcd4a5416d] ->
/usr/lib/dovecot/libdovecot-storage.so.0(mailbox_move+0x23)
[0x7fbcd4a54333] -> dovecot/imap(+0xf9c5) [0x557cf98629c5] ->
dovecot/imap(command_exec+0xa6) [0x557cf986f196] -> dovecot/imap(+0x1a4c2)
[0x557cf986d4c2] -> dovecot/imap(+0x1a550) [0x557cf986d550] ->
dovecot/imap(client_handle_input+0x195) [0x557cf986d915] ->
dovecot/imap(client_input+0x85) [0x557cf986de25] ->
/usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x4c) [0x7fbcd4799bdc] ->
/usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run_internal+0x10a)
[0x7fbcd479b09a] ->
/usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0x25) [0x7fbcd4799c65]
-> /usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x38) [0x7fbcd4799e08] ->
/usr/lib/dovecot/libdovecot.so.0(master_service_run+0x13) [0x7fbcd4724f53]
-> dovecot/imap(main+0x322) [0x557cf9860ca2] ->
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7fbcd4348830] ->
dovecot/imap(+0xde1f) [0x557cf9860e1f]
Dec 27 15:21:18 dovecot dovecot: imap(danielebarresi): Fatal: master:
service(imap): child 6907 killed with signal 6 (core dumped)

Dovecot configuration (doveadm -n):

# 2.2.26.0 (23d1de6): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.16 (fed8554)
# OS: Linux 4.4.0-57-generic x86_64 Ubuntu 16.04.1 LTS
auth_cache_negative_ttl = 10 mins
auth_cache_size = 2 M
auth_master_user_separator = *
auth_mechanisms = plain login
first_valid_uid = 12
last_valid_uid = 12
mail_location = maildir:~/Maildir
mail_plugins = acl quota notify mail_log stats lazy_expunge
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 casellecondivise {
  list = children
  location = maildir:%%h/Maildir:INDEXPVT=~/Maildir/shared/%%u
  prefix = Caselle condivise/%%u/
  separator = /
  subscriptions = no
  type = shared
}
namespace expunged {
  hidden = yes
  list = no
  location = maildir:/var/expunged/%n/Expunged
  prefix = EXPUNGED/
  separator = /
}
namespace inbox {
  inbox = yes
  location =
  mailbox Archive {
    auto = subscribe
    special_use = \Archive
  }
  mailbox Drafts {
    auto = subscribe
    special_use = \Drafts
  }
  mailbox Junk {
    auto = subscribe
    special_use = \Junk
  }
  mailbox Sent {
    auto = subscribe
    special_use = \Sent
  }
  mailbox Trash {
    auto = subscribe
    special_use = \Trash
  }
  prefix =
  separator = /
  type = private
}
passdb {
  args = /etc/dovecot/dovecot-ldap.conf.ext
  driver = ldap
}
plugin {
  acl = vfile:/etc/dovecot/global-acls:cache_secs=300
  acl_shared_dict = file:/etc/dovecot/shared/shared-mailboxes
  lazy_expunge = EXPUNGED/
  lazy_expunge_only_last_instance = yes
  mail_log_events = delete copy flag_change save undelete expunge
  mail_log_fields = uid box msgid size
  quota = maildir:user quota
  quota_exceeded_message = (Quota exceeded) La casella di posta elettronica
del destinatario è piena.
  quota_rule = *:storage=1G
  quota_rule2 = Trash:storage=+100M
  quota_warning = storage=95%% quota-warning 95 %u
  quota_warning2 = storage=100%% quota-warning 100 %u
  sieve = file:~/sieve;active=~/.dovecot.sieve
  stats_command_min_time = 1 mins
  stats_domain_min_time = 12 hours
  stats_ip_min_time = 12 hours
  stats_memory_limit = 32 M
  stats_refresh = 30 secs
  stats_session_min_time = 15 mins
  stats_track_cmds = yes
  stats_user_min_time = 1 hours
}
protocols = " imap sieve"
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = mail
    mode = 0666
    user = postfix
  }
  unix_listener auth-userdb {
    group = mail
    user = mail
  }
}
service dict {
  unix_listener dict {
    group = mail
    mode = 0600
    user = mail
  }
}
service imap-login {
  process_limit = 300
  process_min_avail = 2
}
service managesieve-login {
  inet_listener sieve {
    port = 4190
  }
}
service quota-warning {
  executable = script /etc/dovecot/scripts/quota-warning.sh
  unix_listener quota-warning {
    group = mail
    user = mail
  }
}
service stats {
  fifo_listener stats-mail {
    mode = 0600
    user = mail
  }
}
ssl = required
ssl_cert = </etc/ssl/certs/pac.apg23.org.pem
ssl_key =  # hidden, use -P to show it
userdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  default_fields = uid=mail gid=mail home=/var/mail/%u master_user=%u
  driver = sql
}
userdb {
  args = /etc/dovecot/dovecot-ldap.conf.ext
  default_fields = uid=mail gid=mail home=/var/mail/%u master_user=%u
  driver = ldap
}
protocol lda {
  mail_plugins = acl quota notify mail_log stats lazy_expunge sieve
}
protocol imap {
  mail_max_userip_connections = 25
  mail_plugins = acl quota notify mail_log stats lazy_expunge imap_quota
imap_stats
}

I tested this with different users with the same result.
I tested and reproduced the error with Thunderbird and Roundcube.
The Apple Mail client uses IMAP COPY + DELETE, instead of IMAP MOVE, and no
errors are reported. So I think it's related to the IMAP MOVE
implementation on Dovecot server.

Has anyone seen the same error?
Any suggestions? Is this a Dovecot bug?

---
Daniele Barresi