Core was generated by `dovecot/imap'.                                                                                                      
Program terminated with signal 11, Segmentation fault.                                                                                     
#0  list_unescape_str (dest=<value optimized out>, str=0x6c8597 "sharing.user", ns=<value optimized out>) at listescape-plugin.c:91        
91                      if (*str == mlist->escape_char &&                                                                                  
(gdb) bt full                                                                                                                              
#0  list_unescape_str (dest=<value optimized out>, str=0x6c8597 "sharing.user", ns=<value optimized out>) at listescape-plugin.c:91        
        mlist = 0x0                                                                                                                        
        num = <value optimized out>                                                                                                        
#1  listescape_mailbox_list_iter_next (dest=<value optimized out>, str=0x6c8597 "sharing.user", ns=<value optimized out>)                  
    at listescape-plugin.c:211                                                                                                             
        mlist = <value optimized out>                                                                                                      
        ns = 0x650e20                                                                                                                      
        liter = 0x647dd8                                                                                                                   
        info = 0x6885d0                                                                                                                    
        __FUNCTION__ = "listescape_mailbox_list_iter_next"                                                                                 
#2  0x00007fd3fa3755c8 in acl_mailbox_list_iter_next_info (ctx=<value optimized out>) at acl-mailbox-list.c:206                            
        alist = 0x647b70                                                                                                                   
#3  acl_mailbox_list_iter_next (ctx=<value optimized out>) at acl-mailbox-list.c:369                                                       
        ctx = 0x6f5120                                                                                                                     
        info = 0x620310                                                                                                                    
        ret = 6423312                                                                                                                      
#4  0x00007fd3fb1a92ea in mailbox_list_iter_next (ctx=0x20) at mailbox-list.c:1029                                                         
        info = <value optimized out>                                                                                                       
#5  0x000000000040bc89 in list_namespace_mailboxes (ctx=<value optimized out>) at cmd-list.c:373                                           
        info = 0x645480                                                                                                                    
        flags = 6575088                                                                                                                    
        str = 0x620310                                                                                                                     
        ret = 0                                                                                                                            
        ns = 0x7fff9245f458                                                                                                                
        name = 0x6203c8 ""                                                                                                                 
#6  cmd_list_continue (ctx=<value optimized out>) at cmd-list.c:788                                                                        
        _data_stack_cur_id = 4                                                                                                             
        ctx = 0x656d88                                                                                                                     
#7  0x000000000040cb86 in cmd_list_full (cmd=0x656c88, lsub=true) at cmd-list.c:953                                                        
        client = 0x656528                                                                                                                  
        args = 0x659520                                                                                                                    
        list_args = 0x7fd3faf4fa18                                                                                                         
        arg_count = <value optimized out>                                                                                                  
        ctx = 0x656d88                                                                                                                     
        patterns = {arr = {buffer = 0x656dd8, element_size = 8}, v = 0x656dd8, v_modifiable = 0x656dd8}                                    
        pattern = 0x6595d8 "Shared/%"                                                                                                      
        patterns_strarr = <value optimized out>                                                                                            
---Type <return> to continue, or q <return> to quit---                                                                                     
#8  0x000000000041021d in client_command_input (cmd=0x656c88) at imap-client.c:660                                                         
        client = 0x656528                                                                                                                  
        command = <value optimized out>                                                                                                    
        __FUNCTION__ = "client_command_input"                                                                                              
#9  0x00000000004102fd in client_command_input (cmd=0x656c88) at imap-client.c:710                                                         
        client = 0x656528                                                                                                                  
        command = 0x6510d0                                                                                                                 
        __FUNCTION__ = "client_command_input"                                                                                              
#10 0x0000000000410525 in client_handle_next_command (remove_io_r=<value optimized out>, client=<value optimized out>) at imap-client.c:751
        size = 25
#11 client_handle_input (remove_io_r=<value optimized out>, client=<value optimized out>) at imap-client.c:763
        _data_stack_cur_id = 3
        ret = false
        remove_io = <value optimized out>
        handled_commands = false
        __FUNCTION__ = "client_handle_input"
#12 0x0000000000410e4f in client_input (client=0x656528) at imap-client.c:802
        cmd = <value optimized out>
        output = 0x656b08
        bytes = <value optimized out>
        __FUNCTION__ = "client_input"
#13 0x00007fd3faf415f5 in io_loop_handler_run (ioloop=<value optimized out>) at ioloop-epoll.c:212
        ctx = 0x6287d0
        event = 0x628840
        list = 0x656be0
        io = 0x656ba0
        tv = {tv_sec = 4, tv_usec = 274466}
        t_id = 2
        msecs = <value optimized out>
        ret = 1
        i = 0
        call = <value optimized out>
#14 0x00007fd3faf40778 in io_loop_run (ioloop=0x6285c0) at ioloop.c:350
No locals.
#15 0x00007fd3faf303c3 in master_service_run (service=0x628490, callback=0x63) at master-service.c:496
No locals.
#16 0x0000000000418de1 in main (argc=1, argv=0x628370) at main.c:358
---Type <return> to continue, or q <return> to quit---
        set_roots = {0x41bf80, 0x0}
        service_flags = <value optimized out>
        storage_service_flags = MAIL_STORAGE_SERVICE_FLAG_DISALLOW_ROOT
        postlogin_socket_path = 0x0
        username = 0x0
        c = <value optimized out>
(gdb)