My log is full of blocks like this: auth(default): pam(?): PAM child process 13576 timed out, killing it auth(default): PAM: kill(13576) failed: No such process

Often, this is recorded for several pids at once.

Occasionally, there's a single burst when a virtual user logs in,
immediately before pam_authenticate() fails and checkpassword is
executed. When this happens, pam() contains the username and remote IP.

Usually, it starts 2 minutes after a login attempt (successful or
not) and repeats every 10 seconds indefinitely. pam() contains
something else: ~87% ? ~ 9% [garbage],master ~ 4% ?,master < 1% [empty]

[garbage] varies; it seems to be constant for an instance of auth,
but I haven't verified this.

Eventually, auth segfaults: Core was generated by `dovecot-auth'. Program terminated with signal 11, Segmentation fault. ... #0 0x08087a68 in str_sanitize_append (dest=0x80a8950, src=0x3d9
<Address 0x3d9 out of bounds>, max_len=64) at str-sanitize.c:11 p = 0x3d9 <Address 0x3d9 out of bounds> #1 0x08057a1d in get_log_str (auth_request=0x80c6a00,
subsystem=0x808f7cd "pam", format=0x808f9ac "PAM child process %s
timed out, killing it", va=0x597f8c5c ":\211\n\b?|\t\b?|\t\b?\214\177Y") at auth-request.c:1121 ip = 0xa <Address 0xa out of bounds> str = (string_t *) 0x80a8950 #2 0x08057c62 in auth_request_log_error (auth_request=0x80c6a00,
subsystem=0x808f7cd "pam", format=0x808f9ac "PAM child process %s
timed out, killing it") at auth-request.c:1177 va = 0x597f8c5c ":\211\n\b?|\t\b?|\t\b?\214\177Y" #3 0x080658ee in pam_child_timeout (context=0x0) at passdb-pam.c:537 request = (struct pam_auth_request *) 0x80c6de8 iter = (struct hash_iterate_context *) 0x80bcdb0 key = (void *) 0xa9e value = (void *) 0x80c6de8 timeout = 1182548633 #4 0x08079fc5 in io_loop_handle_timeouts (ioloop=0x80b09b0,
update_run_now=true) at ioloop.c:294 t = (struct timeout *) 0x80b4ca8 called_timeouts = (struct timeout *) 0x80b4ca8 tv = {tv_sec = 0, tv_usec = 0} t_id = 2 #5 0x0807b32e in io_loop_handler_run (ioloop=0x80b09b0) at ioloop- epoll.c:175 ctx = (struct ioloop_handler_context *) 0x80b09d8 events = (struct epoll_event *) 0x80b0a18 event = (const struct epoll_event *) 0x80b0a18 list = (struct io_list *) 0x80c42d8 io = (struct io *) 0x0 tv = {tv_sec = 1, tv_usec = 180418} events_count = 12 t_id = 2 msecs = 1181 ret = 0 i = 1 j = 3 call = true #6 0x0807a0a8 in io_loop_run (ioloop=0x80b09b0) at ioloop.c:329 No locals. #7 0x0805d7ee in main (argc=1, argv=0x597f8ec4) at main.c:321 foreground = false

My config (Gentoo Linux hardened/x86/2.6): # 1.0.1: /etc/dovecot/dovecot.conf listen: [::1] ssl_listen: [::] ssl_cert_file: /etc/ssl/misfeature.net/crt ssl_key_file: /etc/ssl/misfeature.net/key ssl_cipher_list: HIGH login_dir: /var/run/dovecot/login login_executable: /usr/libexec/dovecot/imap-login login_greeting_capability: yes verbose_proctitle: yes first_valid_uid: 1000 first_valid_gid: 100 mail_location: maildir:~/mail mail_debug: yes maildir_copy_with_hardlinks: yes mail_drop_priv_before_exec: yes imap_client_workarounds: delay-newmail outlook-idle auth default: verbose: yes debug: yes passdb: driver: pam args: * passdb: driver: checkpassword args: /usr/local/bin/checkpassword userdb: driver: passwd userdb: driver: prefetch socket: type: listen client: path: /var/spool/postfix/private/auth mode: 432 user: postfix group: postfix

I turned on the various logging options while investigating this
problem; the messages appear even without.

-- TA