This is a Samba member server on Centos8 with Samba 4.13.2 from Sernet. Twice now we had a segfault with the following error:

2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:32.314181,  0] ../../lib/util/fault.c:159(smb_panic_log)
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:  ===============================================================
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:32.314278,  0] ../../lib/util/fault.c:163(smb_panic_log)
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:  INTERNAL ERROR: Signal 11: Segmentation fault in pid 15504 (4.13.2-SerNet-RedHat-4.el7)
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:32.314313,  0] ../../lib/util/fault.c:168(smb_panic_log)
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:  If you are running a recent Samba version, and if you think this problem is not yet fixed in the latest versions, please consider reporting this bug, see https://wiki.samba.org/index.php/Bug_Reporting
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:32.314331,  0] ../../lib/util/fault.c:169(smb_panic_log)
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:  ===============================================================
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:32.314344,  0] ../../lib/util/fault.c:171(smb_panic_log)
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:  PANIC (pid 15504): Signal 11: Segmentation fault in 4.13.2-SerNet-RedHat-4.el7
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:32.346651,  0] ../../lib/util/fault.c:275(log_stack_trace)
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:  BACKTRACE: 39 stack frames:
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #0 /usr/lib64/samba/libsamba-util.so.0(log_stack_trace+0x2d) [0x7fd05499bb5b]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #1 /usr/lib64/samba/libsamba-util.so.0(smb_panic_log+0x166) [0x7fd05499bd8e]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #2 /usr/lib64/samba/libsamba-util.so.0(smb_panic+0x23) [0x7fd05499bdb3]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #3 /usr/lib64/samba/libsamba-util.so.0(+0x19fe8) [0x7fd05499bfe8]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #4 /lib64/libpthread.so.0(+0xf630) [0x7fd050fb1630]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #5 /usr/lib64/samba/libsmbd-base-samba4.so(+0x1aff76) [0x7fd0545f8f76]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #6 /usr/lib64/samba/libsmbd-base-samba4.so(close_file+0xbc5) [0x7fd0545fa3a2]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #7 /usr/lib64/samba/libsmbd-base-samba4.so(file_close_user+0x2a) [0x7fd05458f212]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #8 /usr/lib64/samba/libsmbd-base-samba4.so(smbXsrv_session_logoff+0x50) [0x7fd0546470b3]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #9 /usr/lib64/samba/libsmbd-base-samba4.so(+0x1fe376) [0x7fd054647376]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #10 /usr/lib64/samba/libsmbd-base-samba4.so(+0x1fe44c) [0x7fd05464744c]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #11 /usr/lib64/samba/libdbwrap-samba4.so(+0x525f) [0x7fd04f1b025f]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #12 /usr/lib64/samba/libdbwrap-samba4.so(+0x53fd) [0x7fd04f1b03fd]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #13 /usr/lib64/samba/libdbwrap-samba4.so(dbwrap_traverse+0xa) [0x7fd04f1aea53]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #14 /usr/lib64/samba/libsmbd-base-samba4.so(smbXsrv_session_logoff_all+0xa5) [0x7fd054647621]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #15 /usr/lib64/samba/libsmbd-base-samba4.so(+0x203e67) [0x7fd05464ce67]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #16 /usr/lib64/samba/libsmbd-base-samba4.so(smbd_reinit_after_fork+0) [0x7fd05464d271]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #17 /usr/lib64/samba/libsmbd-shim-samba4.so(exit_server_cleanly+0x12) [0x7fd051b3ea53]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #18 /usr/lib64/samba/libsmbd-base-samba4.so(smbd_server_connection_terminate_ex+0x31a) [0x7fd054623edf]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #19 /usr/lib64/samba/libsmbd-base-samba4.so(+0x1dfcc6) [0x7fd054628cc6]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #20 /usr/lib64/samba/libtevent.so.0(tevent_common_invoke_fd_handler+0x82) [0x7fd053c350f0]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #21 /usr/lib64/samba/libtevent.so.0(+0xc475) [0x7fd053c3b475]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #22 /usr/lib64/samba/libtevent.so.0(+0xa1e7) [0x7fd053c391e7]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #23 /usr/lib64/samba/libtevent.so.0(_tevent_loop_once+0xa3) [0x7fd053c34916]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #24 /usr/lib64/samba/libtevent.so.0(tevent_common_loop_wait+0x17) [0x7fd053c34b04]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #25 /usr/lib64/samba/libtevent.so.0(+0xa197) [0x7fd053c39197]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #26 /usr/lib64/samba/libtevent.so.0(_tevent_loop_wait+0xa) [0x7fd053c34b6c]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #27 /usr/lib64/samba/libsmbd-base-samba4.so(smbd_process+0xa4d) [0x7fd05461575d]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #28 /usr/sbin/smbd(+0xc75c) [0x55570363b75c]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #29 /usr/lib64/samba/libtevent.so.0(tevent_common_invoke_fd_handler+0x82) [0x7fd053c350f0]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #30 /usr/lib64/samba/libtevent.so.0(+0xc475) [0x7fd053c3b475]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #31 /usr/lib64/samba/libtevent.so.0(+0xa1e7) [0x7fd053c391e7]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #32 /usr/lib64/samba/libtevent.so.0(_tevent_loop_once+0xa3) [0x7fd053c34916]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #33 /usr/lib64/samba/libtevent.so.0(tevent_common_loop_wait+0x17) [0x7fd053c34b04]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #34 /usr/lib64/samba/libtevent.so.0(+0xa197) [0x7fd053c39197]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #35 /usr/lib64/samba/libtevent.so.0(_tevent_loop_wait+0xa) [0x7fd053c34b6c]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #36 /usr/sbin/smbd(main+0x1e01) [0x55570363d5fe]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #37 /lib64/libc.so.6(__libc_start_main+0xf5) [0x7fd050bf6555]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:   #38 /usr/sbin/smbd(+0x6ab9) [0x555703635ab9]
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:32.346973,  0] ../../source3/lib/util.c:838(smb_panic_s3)
2020-12-02T18:25:32+01:00 lx-sv-09 smbd_audit:  smb_panic(): calling panic action [/usr/share/samba/scripts/panic-action 15504]
2020-12-02T18:25:34+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:34.355089,  0] ../../source3/lib/util.c:846(smb_panic_s3)
2020-12-02T18:25:34+01:00 lx-sv-09 smbd_audit:  smb_panic(): action returned status 0
2020-12-02T18:25:34+01:00 lx-sv-09 smbd_audit: [2020/12/02 18:25:34.355945,  0] ../../source3/lib/dumpcore.c:318(dump_core)
2020-12-02T18:25:34+01:00 lx-sv-09 smbd_audit:  coredump is handled by helper binary specified at /proc/sys/kernel/core_pattern
2020-12-02T18:25:34+01:00 lx-sv-09 smbd_audit: 
2020-12-02T18:25:34+01:00 lx-sv-09 abrt-hook-ccpp: Process 15504 (smbd) of user 0 killed by SIGABRT - dumping core



There is nothing in the logs to indicate why this happens.