cram-md5 cache problem

[d tbsky]

hi:
     I was using scientific linux 6 and had cache problem. I upgrade
to scientific linux 7  but the problem is the same, so I try to find
out why.

    dovecot version:  2.2.10.
    postfix + postfixadmin environment. use dovecot-lda to deliver local mail.

    if I enable cache with "auth_cache_size = 102400" and enable
cram-md5 with "auth_mechanisms = plain login cram-md5". I have cache
problem:

    if I change password at postfixadmin, I can not use the new
password to login imap when old password is cached. dovecot log below:

Jun 28 11:50:32 auth: Debug: client in: AUTH    6       CRAM-MD5
 service=imap    securedsession=xjn534sZ9gB/AAAB lip=127.0.0.1
rip=127.0.0.1   lport=143       rport=36342
Jun 28 11:50:32 auth: Debug: client passdb out: CONT    6
PDQzNTU5NTA4MTQxODg5NzUuMTQzNTQ2MzQzMkBtYWlsLmxoeS5jb20udHc+
Jun 28 11:50:32 auth: Debug: client in: CONT<hidden>
Jun 28 11:50:32 auth: Debug:
cache(test at test.example.com,127.0.0.1,<xjn534sZ9gB/AAAB>): hit:
<hidden>    user=test at test.example.com
userdb_home=/share/postfix/domains/test.example.com/test/home
userdb_mail=maildir:/share/postfix/domains/test.example.com/test
userdb_uid=143  userdb_gid=143
Jun 28 11:50:32 auth: Info:
cram-md5(test at test.example.com,127.0.0.1,<xjn534sZ9gB/AAAB>): password
mismatch
Jun 28 11:50:34 auth: Debug: client passdb out: FAIL    6
user=test at test.example.com
Jun 28 11:50:34 imap-login: Debug: Ignoring unknown passdb extra field:
Jun 28 11:50:34 imap-login: Info: Disconnected (auth failed, 1
attempts in 2 secs): user=<test at test.example.com>, method=CRAM-MD5,
rip=127.0.0.1, lip=127.0.0.1, secured, session=<xjn534sZ9gB/AAAB>



    if I disable "cram-md5" with "auth_mechanisms = plain login".
everything is fine. dovecot log below:

Jun 28 11:32:24 auth: Debug:
cache(test at test.example.com,127.0.0.1,<WNsin4sZ6gB/AAAB>): hit:
<hidden>    user=test at test.example.com
userdb_home=/share/postfix/domains/test.example.com/test/home
userdb_mail=maildir:/share/postfix/domains/test.example.com/test
userdb_uid=143  userdb_gid=143
Jun 28 11:32:24 auth: Info:
cache(test at test.example.com,127.0.0.1,<WNsin4sZ6gB/AAAB>): Password
mismatch
Jun 28 11:32:24 auth-worker(3711): Debug:
sql(test at test.example.com,127.0.0.1): query: SELECT username as user,
password, '/share/postfix/domains/test.example.com/test/home' as
userdb_home, 'maildir:/share/postfix/domains/test.example.com/test' as
userdb_mail, 143 as userdb_uid, 143 as userdb_gid FROM mailbox WHERE
username = 'test at test.example.com' AND active = '1'
Jun 28 11:32:24 auth: Debug: client passdb out: OK      15
user=test at test.example.com
Jun 28 11:32:24 auth: Debug: master in: REQUEST 1951268865      3672
 15      0b198494a7e732324f6d6c507b25c13e        session_pid=3956
  request_auth_token
Jun 28 11:32:24 auth: Debug:
prefetch(test at test.example.com,127.0.0.1,<WNsin4sZ6gB/AAAB>): success

Regards,
tbskyd