Stupid users cause weird crashes in the DNS code ...

[Richard Sharpe]

Hi folks,

I didn't follow the instructions carefully enough.

I set up resolv.conf to point at 127.0.0.1 and an upstream nameserver
(10.20.1.100).

During provisioning that created an entry of 'dns resolver = 127.0.0.1'.

That resulted in the following crash. Looks like a bug.

Provisioning should not use any of the aliases for the current system
as forwarders.

In addition, perhaps the code should not crash if it gets a timeout.

4.19.0rc4.

----------------------------
[2023/09/01 14:12:57.423713, 10, pid=24521, effective(0, 0), real(0,
0), class=dns] ../../source4/dns_server/dns_server.c:234(dns_process_done)
  dns_process_done: dns_server_process_query_recv(): WERR_SEM_TIMEOUT
[2023/09/01 14:12:57.423754,  5, pid=24521, effective(0, 0), real(0,
0), class=dns] ../../source4/dns_server/dnsserver_common.c:72(werr_to_dns_err)
  No mapping exists for WERR_SEM_TIMEOUT
[2023/09/01 14:12:57.423781,  5, pid=24521, effective(0, 0), real(0,
0), class=dns] ../../source4/dns_server/dns_server.c:260(dns_process_recv)
  dns_process_recv: FAILURE: WERR_SEM_TIMEOUT from
tevent_req[0x619001b58100/../../source4/dns_server/dns_server.c:129]:
state[2] error[0 (0x0)]  state[struct dns_process_state
(0x619001b582e0)] timer[(nil)]
finish[../../source4/dns_server/dns_server.c:236]
[2023/09/01 14:12:57.424336, 10, pid=24521, effective(0, 0), real(0,
0)] ../../lib/util/util.c:578(dump_data)
  [0000] 2F 42 81 02 00 01 00 00   00 00 00 00 0B 68 61 6D   /B...... .....ham
  [0010] 6D 65 72 73 70 61 63 65   0A 63 6F 6D 70 6C 69 61   merspace .complia
  [0020] 6E 63 65 11 66 6C 65 78   6E 65 74 6F 70 65 72 61   nce.flex netopera
  [0030] 74 69 6F 6E 73 03 63 6F   6D 00 00 01 00 01         tions.co m.....
  dns_cli_request_udp_done:
===============================================================
[2023/09/01 14:12:57.424720,  0, pid=24521, effective(0, 0), real(0,
0)] ../../lib/util/fault.c:185(smb_panic_log)
  INTERNAL ERROR: Signal 11: Segmentation fault in samba (dns[master])
(task[dns] pre-fork master) pid 24521 (4.19.0rc4)
[2023/09/01 14:12:57.424838,  0, pid=24521, effective(0, 0), real(0,
0)] ../../lib/util/fault.c:190(smb_panic_log)
  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
[2023/09/01 14:12:57.424908,  0, pid=24521, effective(0, 0), real(0,
0)] ../../lib/util/fault.c:191(smb_panic_log)
-----------------------------------------------

-- 
Regards,
Richard Sharpe
(何以解憂？唯有杜康。--曹操)(传说杜康是酒的发明者)