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ID Category Severity Reproducibility Date Submitted Last Update
0000025 [MyDNS-NG] Global block always 2009-07-01 11:56 2009-12-16 16:31
Reporter ibc View Status public  
Assigned To howardwilkinson
Priority normal Resolution no change required  
Status resolved   Product Version 1.2.8.27
Summary 0000025: segfault at 0 rip 42763f rsp
Description - Debian Lenny 64 bits
- mydns-1.2.8.27 (compiled from sources)

I have 3-4 domains configured in my DNS server, and for some of them mydns doesn't reply (I get a DNS error). However, the mos important point here is that syslog periodically shows how some mydns process dies (permanently):

--------------------
Jul 1 12:37:50 myserver kernel: mydns[24762]: segfault at 0 rip 42763f rsp 7fffdbab6ba0 error 6
Jul 1 12:37:50 myserver kernel: grsec: From XX.XXX.XX.XXX: signal 11 sent to /usr/local/sbin/mydns[mydns:24762] uid/euid:65534/65534 gid/egid:65534/65534, parent /usr/local/sbin/mydns[mydns:24384] uid/euid:65534/65534 gid/egid:65534/65534
Jul 1 12:37:50 myserver mydns[24384]: pid 24762 exited due to signal 11
Jul 1 12:37:50 myserver mydns[24384]: Server pid 24762 died
--------------------

I've downgraded to mydns-1.1.0 and it works nice.
Is there anything I could try in order to find the problem?
Additional Information
Tags No tags attached.
Attached Files

- Relationships

-  Notes
(0000077)
jorge (administrator)
2009-07-07 22:27

How many servers are you running?
check mydns.conf for:

servers =
(0000078)
ibc (reporter)
2009-07-07 22:31
edited on: 2009-07-07 22:32

I can't find that parameter in mydns.conf, neither in the mydns.conf provided in the sources.

However I find:
  multicpu = 2 (I have two CPU's)

(0000080)
jorge (administrator)
2009-07-07 23:23

Sorry,
I wanted to say:
servers = 0
(0000082)
ibc (reporter)
2009-07-22 20:57

I've tryed with "servers = 0", "1", "2"... in combination with different
values in "multicpu" (-1, 0, 1, 2). In all the cases the segfault remains.
(0000083)
ibc (reporter)
2009-07-22 21:58

It occurs with any 1.2.8.X but doesn't occur with 1.2.7.
(0000084)
jorge (administrator)
2009-07-27 12:09

Anyway, i think this is something with grsecurity.
Can you disable grsec and test with it off?
(0000085)
ibc (reporter)
2009-07-27 20:00

Sorry, it's a hosted server in production (for other services than DNS) with a custom kernel compiled with no modules, and I cannot dissable it.

Could it be enough if I run mydns as root instead of as "nobody"?
(0000104)
jorge (administrator)
2009-11-15 17:37

IF you run MyDNS under GDB, can you get a stracktrace for me?
(0000116)
tlamy (developer)
2009-12-16 16:29

This may be related to a bug in libmysqlclient in Lenny x64, which should have been fixed already.
You can use "taskset" and configure for single CPU usage to prevent the crash.

See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=513204#181 [^] for more details.

Please follow up if the problem still persits.
(0000117)
tlamy (developer)
2009-12-16 16:31

Bug is/was in libmysqlclient15off from Debian, which occured only on x64 multi-CPU environments
See: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=513204#181 [^]

- Issue History
Date Modified Username Field Change
2009-07-01 11:56 ibc New Issue
2009-07-01 12:01 ibc Issue Monitored: ibc
2009-07-07 22:26 jorge Status new => assigned
2009-07-07 22:26 jorge Assigned To => howardwilkinson
2009-07-07 22:27 jorge Note Added: 0000077
2009-07-07 22:31 ibc Note Added: 0000078
2009-07-07 22:32 ibc Note Edited: 0000078
2009-07-07 22:40 jorge Note Added: 0000079
2009-07-07 23:23 jorge Note Deleted: 0000079
2009-07-07 23:23 jorge Note Added: 0000080
2009-07-22 20:57 ibc Note Added: 0000082
2009-07-22 21:58 ibc Note Added: 0000083
2009-07-27 12:09 jorge Note Added: 0000084
2009-07-27 20:00 ibc Note Added: 0000085
2009-11-15 17:37 jorge Note Added: 0000104
2009-12-16 16:29 tlamy Note Added: 0000116
2009-12-16 16:31 tlamy Note Added: 0000117
2009-12-16 16:31 tlamy Status assigned => resolved
2009-12-16 16:31 tlamy Resolution open => no change required


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