Segfault in acl_mailbox_get_aclobj w/ dovecot

Fri Jan 22 23:24:02 UTC 2016

The Wed, 13 Jan 2016 01:33:42 +0100, "D[r]eadlock M"
<m.dreadlock at gmail.com> wrote 

> Hello,
> 
> I've being trying to play with shared mailboxes but experienced a
> segfault: [New LWP 9611]
> Core was generated by `dovecot/imap'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> (gdb) bt f
> #0  0x00007f5b72f429b2 in acl_mailbox_get_aclobj (box=<optimized
> #out>) at
> acl-mailbox.c:31
>         abox = 0x0
> #1  0x00007f5b72d30fcc in cmd_myrights (cmd=0x7f5b75c97480) at
> imap-acl-plugin.c:331
>         ns = <optimized out>
>         box = 0x7f5b75ca4520
>         mailbox = 0x7f5b75c752a8 "shared"
>         orig_mailbox = 0x7f5b75c80be0 "shared"
>         rights = 0x7f5b75c75108
>         str = <optimized out>
> #2  0x00007f5b73f2e09c in command_exec
> #(cmd=cmd at entry=0x7f5b75c97480) at
> imap-commands.c:158
>         hook = 0x7f5b75c7e0f0
>         ret = <optimized out>
> #3  0x00007f5b73f2cfb2 in client_command_input (cmd=0x7f5b75c97480)
> #at
> imap-client.c:778
>         client = 0x7f5b75c96880
>         command = <optimized out>
>         __FUNCTION__ = "client_command_input"
> #4  0x00007f5b73f2d066 in client_command_input (cmd=0x7f5b75c97480)
> #at
> imap-client.c:839
>         client = 0x7f5b75c96880
>         command = <optimized out>
>         __FUNCTION__ = "client_command_input"
> #5  0x00007f5b73f2d39d in client_handle_next_command
> (remove_io_r=<synthetic pointer>, client=0x7f5b75c96880) at
> imap-client.c:877
> No locals.
> #6  client_handle_input (client=0x7f5b75c96880) at imap-client.c:889
>         _data_stack_cur_id = 3
>         remove_io = false
>         handled_commands = true
>         client = 0x7f5b75c96880
> #7  0x00007f5b73f2d745 in client_input (client=0x7f5b75c96880) at
> imap-client.c:931
>         cmd = 0x9f3f2
>         output = 0x7f5b75c972c0
>         bytes = 95
>         __FUNCTION__ = "client_input"
> #8  0x00007f5b73773d0f in io_loop_call_io (io=0x7f5b75c97390) at
> ioloop.c:441
>         ioloop = 0x7f5b75c7d740
>         t_id = 2
>         __FUNCTION__ = "io_loop_call_io"
> #9  0x00007f5b73774d09 in io_loop_handler_run_internal
> (ioloop=ioloop at entry=0x7f5b75c7d740)
> at ioloop-epoll.c:220
>         ctx = 0x7f5b75c7e3d0
>         io = <optimized out>
>         tv = {tv_sec = 1799, tv_usec = 999014}
>         events_count = <optimized out>
>         msecs = <optimized out>
>         ret = 1
>         i = 0
>         j = <optimized out>
>         call = <optimized out>
>         __FUNCTION__ = "io_loop_handler_run_internal"
> #10 0x00007f5b73773d79 in io_loop_handler_run
> (ioloop=ioloop at entry=0x7f5b75c7d740)
> at ioloop.c:488
> No locals.
> #11 0x00007f5b73773df8 in io_loop_run (ioloop=0x7f5b75c7d740) at
> ioloop.c:465
>         __FUNCTION__ = "io_loop_run"
> #12 0x00007f5b7371edc3 in master_service_run
> #(service=0x7f5b75c7d5d0,
> callback=<optimized out>) at master-service.c:566
> No locals.
> #13 0x00007f5b73f21254 in main (argc=1, argv=0x7f5b75c7d390) at
> #main.c:400
>         set_roots = {0x7f5b74145980 <imap_setting_parser_info>, 0x0}
>         login_set = {auth_socket_path = 0x7f5b75c75048 "\001",
> postlogin_socket_path = 0x0, postlogin_timeout_secs = 60, callback =
> 0x7f5b73f371f0 <login_client_connected>, failure_callback =
> 0x7f5b73f36ed0 <login_client_failed>,
>           request_auth_token = 1}
>         service_flags = <optimized out>
>         storage_service_flags = <optimized out>
>         username = 0x0
>         c = <optimized out>
> 
> 
> It happens when my client (mutt) tries to enter the shared/ folder.
> A filtered strace shows (note the 7 seconds between write and read,
> presumely the command sent by mutt):
> 8704  00:40:51.420843
> open("/var/vmail/domain.tld/marc/Maildir/.Sent/dovecot-acl",
> O_RDONLY) = -1 ENOENT (No such file or directory)
> 8704  00:40:51.420978
> stat("/var/vmail/domain.tld/marc/Maildir/dovecot-acl",
> 0x7fffc618dcb0) = -1 ENOENT (No such file or directory)
> 8704  00:40:51.421100 open("/var/vmail/domain.tld/shared-mailboxes",
> O_RDONLY) = 4
> 8704  00:40:51.421800 openat(AT_FDCWD,
> "/var/vmail/domain.tld/marc/Maildir",
> O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 12
> 8704  00:40:51.422217 write(7, "* LIST (\\HasNoChildren \\Sent)
> \"/\" Sent\r\n* LIST (\\Noselect \\HasNoChildren) \"/\" shared\r\n*
> LIST (\\HasNoChildren) \"/\" INBOX\r\na0005 OK List completed.\r
> \n", 147) = 147 8704  00:40:58.235762 <... read resumed> "a0006
> MYRIGHTS \"shared\"\r\na0007 STATUS \"Drafts\" (MESSAGES)\r\na0008
> SELECT \"shared\"\r\n", 8137) = 82
> 
> I admit I've played a little with directories in /var/vmail/ and
> got a few 'permission denied' but I think I fixed them correctly
> (move /var/mail/domain.tld/marc into .../Maildir, who ended being
> root:root)
> 
> To finish, my dovecot -n:
> # 2.2.13: /etc/dovecot/dovecot.conf
> # OS: Linux 3.16.0-4-amd64 x86_64 Debian 8.2
> mail_location = maildir:~/Maildir
> mail_plugins = acl
> namespace {
>   location = maildir:%%h/Maildir:INDEXPVT=~/Maildir/shared/%%n
>   prefix = shared/%%n/
>   separator = /
>   type = shared
> }
> 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 =
>   separator = /
>   type = private
> }
> passdb {
>   args = scheme=SHA512-CRYPT username_format=%u /etc/dovecot/users
>   driver = passwd-file
> }
> plugin {
>   acl = vfile
>   acl_shared_dict = file:/var/vmail/%d/shared-mailboxes
> }
> protocols = " imap lmtp"
> service auth-worker {
>   user = $default_internal_user
> }
> service auth {
>   unix_listener /var/spool/postfix/private/auth {
>     mode = 0666
>   }
> }
> service lmtp {
>   unix_listener /var/spool/postfix/private/dovecot-lmtp {
>     group = postfix
>     mode = 0666
>     user = postfix
>   }
> }
> ssl = required
> ssl_cert = </etc/letsencrypt/live/domain.tld/fullchain.pem
> ssl_key = </etc/letsencrypt/live/domain.tld/privkey.pem
> userdb {
>   args = uid=vmail gid=vmail home=/var/vmail/%d/%n
>   driver = static
> }
> userdb {
>   args = uid=vmail gid=vmail home=/var/vmail/%d/shared/%n
>   driver = static
> }
> protocol imap {
>   mail_plugins = acl imap_acl
> }
> 
> Thanks,
> 
> Marc

Hum, should be fixed by
https://github.com/dovecot/core/commit/f136b0050b3125b466af73984177250b7ed1a3be

But I do not fully understand the commit message, especially the "it
probably should have been a type=public namespace instead". Could I
change my conf to no longer experience the segfault ?

Thanks,

Marc.