[Samba] "Random" crashes of Samba as AD DC

Mauel, Volker v.mauel at fz-juelich.de
Tue Jul 17 16:30:19 UTC 2018 

Hey all,

up until 2 weeks ago my samba DC was running just fine, then it began crashing randomly.
I was using 4.8.0 before, now upgraded to a self-compiled 4.8.3 with default build parameters on an up-to-date centos 7.5 with disabled SELinux and bind9 as DNS backend with samba_dlz.

The log output at log level = 10 is as follows:
Jul 17 14:49:20 hostname samba[4998]: [2018/07/17 14:49:20.587655,  0, pid=4998, effective(0, 0), real(0, 0)] ../lib/util/fault.c:79(fault_report)
Jul 17 14:49:20 hostname samba[4998]:   ===============================================================
Jul 17 14:49:20 hostname samba[4998]: [2018/07/17 14:49:20.587752,  0, pid=4998, effective(0, 0), real(0, 0)] ../lib/util/fault.c:80(fault_report)
Jul 17 14:49:20 hostname samba[4998]:   INTERNAL ERROR: Signal 11 in pid 4998 (4.8.3)
Jul 17 14:49:20 hostname samba[4998]:   Please read the Trouble-Shooting section of the Samba HOWTO
Jul 17 14:49:20 hostname samba[4998]: [2018/07/17 14:49:20.587828,  0, pid=4998, effective(0, 0), real(0, 0)] ../lib/util/fault.c:82(fault_report)
Jul 17 14:49:20 hostname samba[4998]:   ===============================================================
Jul 17 14:49:20 hostname samba[4998]: [2018/07/17 14:49:20.587871,  0, pid=4998, effective(0, 0), real(0, 0)] ../lib/util/fault.c:128(smb_panic_default)
Jul 17 14:49:20 hostname samba[4998]:   smb_panic_default: PANIC (pid 4998): internal error
Jul 17 14:49:20 hostname samba[4998]: [2018/07/17 14:49:20.588558,  0, pid=4998, effective(0, 0), real(0, 0)] ../lib/util/fault.c:261(log_stack_trace)
Jul 17 14:49:20 hostname samba[4998]:   BACKTRACE: 45 stack frames:
Jul 17 14:49:20 hostname samba[4998]:    #0 /usr/local/samba/lib/libsamba-util.so.0(log_stack_trace+0x1f) [0x7f81f95e9332]
Jul 17 14:49:20 hostname samba[4998]:    #1 /usr/local/samba/lib/libsamba-util.so.0(+0x230ad) [0x7f81f95e90ad]
Jul 17 14:49:20 hostname samba[4998]:    #2 /usr/local/samba/lib/libsamba-util.so.0(log_stack_trace+0) [0x7f81f95e9313]
Jul 17 14:49:20 hostname samba[4998]:    #3 /usr/local/samba/lib/libsamba-util.so.0(+0x22fad) [0x7f81f95e8fad]
Jul 17 14:49:20 hostname samba[4998]:    #4 /usr/local/samba/lib/libsamba-util.so.0(+0x22fc2) [0x7f81f95e8fc2]
Jul 17 14:49:20 hostname samba[4998]:    #5 /lib64/libpthread.so.0(+0xf6d0) [0x7f81f98566d0]
Jul 17 14:49:20 hostname samba[4998]:    #6 /usr/local/samba/lib/libsamdb.so.0(+0xf1e0) [0x7f81f74b91e0]
Jul 17 14:49:20 hostname samba[4998]:    #7 /usr/local/samba/lib/libsamdb.so.0(DsCrackNameOneName+0xd6a) [0x7f81f74b7e6b]
Jul 17 14:49:20 hostname samba[4998]:    #8 /usr/local/samba/lib/libsamdb.so.0(dcesrv_drsuapi_CrackNamesByNameFormat+0xef) [0x7f81f74b9b20]
Jul 17 14:49:20 hostname samba[4998]:    #9 /usr/local/samba/lib/libdcerpc-server.so.0(+0x6d8a1) [0x7f81e249d8a1]
Jul 17 14:49:20 hostname samba[4998]:    #10 /usr/local/samba/lib/libdcerpc-server.so.0(+0x70bd8) [0x7f81e24a0bd8]
Jul 17 14:49:20 hostname samba[4998]:    #11 /usr/local/samba/lib/libdcerpc-server.so.0(+0x91f98) [0x7f81e24c1f98]
Jul 17 14:49:20 hostname samba[4998]:    #12 /usr/local/samba/lib/libdcerpc-server.so.0(+0x92a1c) [0x7f81e24c2a1c]
Jul 17 14:49:20 hostname samba[4998]:    #13 /usr/local/samba/lib/libdcerpc-server.so.0(+0x943f2) [0x7f81e24c43f2]
Jul 17 14:49:20 hostname samba[4998]:    #14 /usr/local/samba/lib/private/libtevent.so.0(_tevent_req_notify_callback+0x6a) [0x7f81f8f8421f]
Jul 17 14:49:20 hostname samba[4998]:    #15 /usr/local/samba/lib/private/libtevent.so.0(+0x72f2) [0x7f81f8f842f2]
Jul 17 14:49:20 hostname samba[4998]:    #16 /usr/local/samba/lib/private/libtevent.so.0(_tevent_req_done+0x25) [0x7f81f8f84319]
Jul 17 14:49:20 hostname samba[4998]:    #17 /usr/local/samba/lib/libdcerpc-binding.so.0(+0x1dc3e) [0x7f81f44bec3e]
Jul 17 14:49:20 hostname samba[4998]:    #18 /usr/local/samba/lib/private/libtevent.so.0(_tevent_req_notify_callback+0x6a) [0x7f81f8f8421f]
Jul 17 14:49:20 hostname samba[4998]:    #19 /usr/local/samba/lib/private/libtevent.so.0(+0x72f2) [0x7f81f8f842f2]
Jul 17 14:49:20 hostname samba[4998]:    #20 /usr/local/samba/lib/private/libtevent.so.0(_tevent_req_done+0x25) [0x7f81f8f84319]
Jul 17 14:49:20 hostname samba[4998]:    #21 /usr/local/samba/lib/private/libsamba-sockets-samba4.so(+0xd705) [0x7f81f46d8705]
Jul 17 14:49:20 hostname samba[4998]:    #22 /usr/local/samba/lib/private/libsamba-sockets-samba4.so(+0xd92f) [0x7f81f46d892f]
Jul 17 14:49:20 hostname samba[4998]:    #23 /usr/local/samba/lib/private/libtevent.so.0(_tevent_req_notify_callback+0x6a) [0x7f81f8f8421f]
Jul 17 14:49:20 hostname samba[4998]:    #24 /usr/local/samba/lib/private/libtevent.so.0(+0x72f2) [0x7f81f8f842f2]
Jul 17 14:49:20 hostname samba[4998]:    #25 /usr/local/samba/lib/private/libtevent.so.0(_tevent_req_done+0x25) [0x7f81f8f84319]
Jul 17 14:49:20 hostname samba[4998]:    #26 /usr/local/samba/lib/private/libsamba-sockets-samba4.so(+0xcc55) [0x7f81f46d7c55]
Jul 17 14:49:20 hostname samba[4998]:    #27 /usr/local/samba/lib/private/libtevent.so.0(_tevent_req_notify_callback+0x6a) [0x7f81f8f8421f]
Jul 17 14:49:20 hostname samba[4998]:    #28 /usr/local/samba/lib/private/libtevent.so.0(+0x72f2) [0x7f81f8f842f2]
Jul 17 14:49:20 hostname samba[4998]:    #29 /usr/local/samba/lib/private/libtevent.so.0(+0x7417) [0x7f81f8f84417]
Jul 17 14:49:20 hostname samba[4998]:    #30 /usr/local/samba/lib/private/libtevent.so.0(tevent_common_loop_immediate+0x1f5) [0x7f81f8f835cc]
Jul 17 14:49:20 hostname samba[4998]:    #31 /usr/local/samba/lib/private/libtevent.so.0(+0xedb6) [0x7f81f8f8bdb6]
Jul 17 14:49:20 hostname samba[4998]:    #32 /usr/local/samba/lib/private/libtevent.so.0(+0xbb57) [0x7f81f8f88b57]
Jul 17 14:49:20 hostname samba[4998]:    #33 /usr/local/samba/lib/private/libtevent.so.0(_tevent_loop_once+0x10f) [0x7f81f8f8246a]
Jul 17 14:49:20 hostname samba[4998]:    #34 /usr/local/samba/lib/private/libtevent.so.0(tevent_common_loop_wait+0x25) [0x7f81f8f8277a]
Jul 17 14:49:20 hostname samba[4998]:    #35 /usr/local/samba/lib/private/libtevent.so.0(+0xbbf9) [0x7f81f8f88bf9]
Jul 17 14:49:20 hostname samba[4998]:    #36 /usr/local/samba/lib/private/libtevent.so.0(_tevent_loop_wait+0x2b) [0x7f81f8f8281d]
Jul 17 14:49:20 hostname samba[4998]:    #37 /usr/local/samba/lib/process_model/standard.so(+0x2793) [0x7f81eaacf793]
Jul 17 14:49:20 hostname samba[4998]:    #38 /usr/local/samba/lib/private/libservice-samba4.so(task_server_startup+0x99) [0x7f81f8b60b2b]
Jul 17 14:49:20 hostname samba[4998]:    #39 /usr/local/samba/lib/private/libservice-samba4.so(+0x2bb4) [0x7f81f8b5ebb4]
Jul 17 14:49:20 hostname samba[4998]:    #40 /usr/local/samba/lib/private/libservice-samba4.so(server_service_startup+0x16a) [0x7f81f8b5ed39]
Jul 17 14:49:20 hostname samba[4998]:    #41 /usr/local/samba/sbin/samba(+0x5800) [0x557a988b4800]
Jul 17 14:49:20 hostname samba[4998]:    #42 /usr/local/samba/sbin/samba(main+0x3f) [0x557a988b4901]
Jul 17 14:49:20 hostname samba[4998]:    #43 /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f81f6cf1445]
Jul 17 14:49:20 hostname samba[4998]:    #44 /usr/local/samba/sbin/samba(+0x3719) [0x557a988b2719]

Since i'm currently not at work myself i could not tell you about any specific event causing this to happen.
One thing i did notice, is that the crash appears to happen in a process that is previously unknown. (as in: pid 4998 does not appear in the journal any time before this crash happens).
Another thing, that makes this situation worse, is that this process seems to block the other samba processes. once this crash occured, there won't be any answer from the DC until it is completely killed and restarted, but the systemd service is configured to always keep the service running.

If you need anything else, please let me know.

Thanks for your help.

Volker Mauel


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