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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 Platform
Status resolved   OS
Projection none   OS Version
ETA none Fixed in Version Product Version 1.2.8.27
  Target Version Product Build
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?
Steps To Reproduce
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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