winbind_cache.tdb contains very old entry, created yet by samba 4.6: # tdbdump -k "U/S-1-5-21-1546016247-1299368408-480117447-6366" winbindd_cache.tdb \00\00\00\00\EA<\94\04\AF\D8\F5^\00\00\00\00\11<username>\FF\0B/home/%D/%U\0A/bin/false\FF\FF\FF\FF-S-1-5-21-1546016247-1299368408-480117447-6366,S-1-5-21-1546016247-1299368408-480117447-513 In https://github.com/samba-team/samba/commit/d0f1d761b5765df8525f991554ffd333d4a247d6 format of the "U/<SID>" entries has changed, new fields were added. Normally this cache entry is expired after winbind cache time (default = 5min), so usually this is not a problem. However, if domain->sequence_number is DOM_SEQUENCE_NONE, centry_expired() returns True, and wcache_query_user() tries to parse old entry using new format, and fails. (gdb) bt #0 0x00007fe495775f47 in __nptl_clear_internal_signals (set=0x7ffcb996ab50) at ../sysdeps/unix/sysv/linux/nptl-signals.h:49 #1 __libc_signal_block_app (set=0x7ffcb996ab50) at ../sysdeps/unix/sysv/linux/nptl-signals.h:69 #2 __GI_raise (sig=0) at ../sysdeps/unix/sysv/linux/raise.c:40 #3 0x00007fe4957778b1 in __GI_abort () at abort.c:104 #4 0x00007fe49a6eeb58 in dump_core () at ../../source3/lib/dumpcore.c:338 #5 0x00007fe49a6de449 in smb_panic_s3 (why=0x555e6e57472c "centry_string") at ../../source3/lib/util.c:861 #6 0x00007fe49e3cda31 in smb_panic (why=0x555e6e57472c "centry_string") at ../../lib/util/fault.c:174 #7 0x0000555e6e4ba99a in centry_string (centry=0x7fe4844c1260, mem_ctx=0x7fe4844c58e0) at ../../source3/winbindd/winbindd_cache.c:321 #8 0x0000555e6e4bab6a in centry_sid (centry=0x7fe4844c1260, sid=0x7ffcb996b020) at ../../source3/winbindd/winbindd_cache.c:371 #9 0x0000555e6e4c0418 in wcache_query_user (domain=0x7fe484441260, mem_ctx=0x7fe484465860, user_sid=0x7ffcb996b180, info=0x7ffcb996afe0) at ../../source3/winbindd/winbindd_cache.c:2305 #10 0x0000555e6e4c0527 in wcache_query_user_fullname (domain=0x7fe484441260, mem_ctx=0x7fe484465860, user_sid=0x7ffcb996b180, full_name=0x7fe4844658a8) at ../../source3/winbindd/winbindd_cache.c:2335 #11 0x0000555e6e4cf2ca in winbind_dual_SamLogon (domain=0x7fe484441260, mem_ctx=0x7fe4844c58e0, interactive=false, logon_parameters=2080, name_user=0x7ffcb996b754 "juliano.schneiker", name_domain=0x7ffcb996b854 "LILIUM", workstation=0x7ffcb996bb5c "DE-C-W25", logon_id=9431387616283419405, client_name=0x7ffcb996b728 "nss_winbind", client_pid=32467, chal=0x7ffcb996b748 "\251Y\266\202cM\274G \b", lm_response=..., nt_response=..., remote=0x7fe48448a6e0, local=0x7fe48448aa60, authoritative=0x7ffcb996b285 "\001\006", skip_sam=false, flags=0x7ffcb996b28c, _validation_level=0x7ffcb996b286, _validation=0x7ffcb996b290) at ../../source3/winbindd/winbindd_pam.c:2618 #12 0x0000555e6e4cf8de in winbindd_dual_pam_auth_crap (domain=0x7fe484441260, state=0x7ffcb996b578) at ../../source3/winbindd/winbindd_pam.c:2720 #13 0x0000555e6e4edf4d in child_process_request (child=0x7fe48452c660, state=0x7ffcb996b578) at ../../source3/winbindd/winbindd_dual.c:771 #14 0x0000555e6e4f0878 in child_handler (ev=0x7fe48446e560, fde=0x7fe4844c9200, flags=1, private_data=0x7ffcb996b570) at ../../source3/winbindd/winbindd_dual.c:1664 #15 0x00007fe49cf8d085 in tevent_common_invoke_fd_handler (fde=0x7fe4844c9200, flags=1, removed=0x0) at ../../lib/tevent/tevent_fd.c:138 #16 0x00007fe49cf97aec in epoll_event_loop (epoll_ev=0x7fe48442c580, tvalp=0x7ffcb996b460) at ../../lib/tevent/tevent_epoll.c:736 #17 0x00007fe49cf981cf in epoll_event_loop_once (ev=0x7fe48446e560, location=0x555e6e58a078 "../../source3/winbindd/winbindd_dual.c:1883") at ../../lib/tevent/tevent_epoll.c:937 #18 0x00007fe49cf94931 in std_event_loop_once (ev=0x7fe48446e560, location=0x555e6e58a078 "../../source3/winbindd/winbindd_dual.c:1883") at ../../lib/tevent/tevent_standard.c:110 #19 0x00007fe49cf8c2a4 in _tevent_loop_once (ev=0x7fe48446e560, location=0x555e6e58a078 "../../source3/winbindd/winbindd_dual.c:1883") at ../../lib/tevent/tevent.c:772 #20 0x0000555e6e4f1440 in fork_domain_child (child=0x7fe48452c660) at ../../source3/winbindd/winbindd_dual.c:1883 #21 0x0000555e6e4eca86 in wb_child_request_waited (subreq=0x0) at ../../source3/winbindd/winbindd_dual.c:263 #22 0x00007fe49cf8e91e in _tevent_req_notify_callback (req=0x7fe4844d6200, location=0x7fe49cf98868 "../../lib/tevent/tevent_queue.c:355") at ../../lib/tevent/tevent_req.c:141 #23 0x00007fe49cf8ea7f in tevent_req_finish (req=0x7fe4844d6200, state=TEVENT_REQ_DONE, location=0x7fe49cf98868 "../../lib/tevent/tevent_queue.c:355") at ../../lib/tevent/tevent_req.c:193 #24 0x00007fe49cf8eaac in _tevent_req_done (req=0x7fe4844d6200, location=0x7fe49cf98868 "../../lib/tevent/tevent_queue.c:355") at ../../lib/tevent/tevent_req.c:199 #25 0x00007fe49cf8e2af in tevent_queue_wait_trigger (req=0x7fe4844d6200, private_data=0x0) at ../../lib/tevent/tevent_queue.c:355 #26 0x00007fe49cf8dcbd in tevent_queue_immediate_trigger (ev=0x7fe48446e560, im=0x7fe48452c7e0, private_data=0x7fe48442dde0) at ../../lib/tevent/tevent_queue.c:149 #27 0x00007fe49cf8d812 in tevent_common_invoke_immediate_handler (im=0x7fe48452c7e0, removed=0x0) at ../../lib/tevent/tevent_immediate.c:166 #28 0x00007fe49cf8d918 in tevent_common_loop_immediate (ev=0x7fe48446e560) at ../../lib/tevent/tevent_immediate.c:203 #29 0x00007fe49cf98135 in epoll_event_loop_once (ev=0x7fe48446e560, location=0x555e6e56a9d0 "../../source3/winbindd/winbindd.c:1949") at ../../lib/tevent/tevent_epoll.c:918 #30 0x00007fe49cf94931 in std_event_loop_once (ev=0x7fe48446e560, location=0x555e6e56a9d0 "../../source3/winbindd/winbindd.c:1949") at ../../lib/tevent/tevent_standard.c:110 #31 0x00007fe49cf8c2a4 in _tevent_loop_once (ev=0x7fe48446e560, location=0x555e6e56a9d0 "../../source3/winbindd/winbindd.c:1949") at ../../lib/tevent/tevent.c:772 #32 0x0000555e6e4a4122 in main (argc=3, argv=0x7ffcb996d448) at ../../source3/winbindd/winbindd.c:1949 (gdb) f 9 #9 0x0000555e6e4c0418 in wcache_query_user (domain=0x7fe484441260, mem_ctx=0x7fe484465860, user_sid=0x7ffcb996b180, info=0x7ffcb996afe0) at ../../source3/winbindd/winbindd_cache.c:2305 2305 ../../source3/winbindd/winbindd_cache.c: No such file or directory. (gdb) p domain->online $3 = true (gdb) p domain->sequence_number $4 = 4294967295 (gdb) p *centry $5 = { status = { v = 0 }, sequence_number = 76823786, timeout = 1593170095, <---- Fri, 26 Jun 2020 11:14:55 GMT data = 0x7fe4845862e0 "", len = 153, ofs = 122 } (gdb) p *info $6 = { domain_name = 0x7fe48448ab60 "<username>", acct_name = 0x0, full_name = 0x7fe484489a40 "/home/%D/%U", homedir = 0x7fe484489ab0 "/bin/false", shell = 0x0, uid = 771751935, primary_gid = 758197587, primary_group_name = 0x7fe4845863e0 "-21-1546016247-1299368408-480117447-6366,S-1-5-21-154", user_sid = { sid_rev_num = 224 '\340', num_auths = -45 '\323', id_auth = "R\204\344\177\000", sub_auths = {2336, 0, 0, 0, 0, 2961362203, 1441812, 32764, 2220271360, 32740, 917516, 32764, 2220382208, 32740, 2220023776} }, group_sid = { sid_rev_num = 228 '\344', num_auths = 127 '\177', id_auth = "\000\000\000\000\000", sub_auths = {0, 16, 0, 0, 0, 0, 0, 0, 0, 6, 0, 2220025696, 32740, 2220026272, 32740} } } [2021/08/04 05:45:00.444649, 1, pid=17348] ../../source3/libads/ldap.c:565(ads_find_dc) ads_find_dc: name resolution for realm '<realm>' (domain '<DOMAIN>') failed: NT_STATUS_NO_LOGON_SERVERS [2021/08/04 05:45:00.463066, 1, pid=17348] ../../source3/libads/ldap.c:565(ads_find_dc) ads_find_dc: name resolution for realm '<realm>' (domain '<DOMAIN>') failed: NT_STATUS_NO_LOGON_SERVERS [2021/08/04 05:45:00.463125, 1, pid=17348, class=winbind] ../../source3/winbindd/winbindd_ads.c:152(ads_cached_connection_connect) ads_connect for domain <DOMAIN> failed: No logon servers are currently available to service the logon request. [2021/08/04 05:45:00.463158, 0, pid=17348, class=winbind] ../../source3/winbindd/winbindd_cache.c:217(centry_check_bytes) centry corruption? needed 54 bytes, have 31 [2021/08/04 05:45:00.463187, 0, pid=17348] ../../source3/lib/util.c:830(smb_panic_s3) PANIC (pid 17348): centry_string