CentOS Bug Tracker - CentOS-6
View Issue Details
0005811CentOS-6sendmailpublic2012-07-09 22:302013-03-02 21:26
PlatformOSOS Version
Product Version 
Target VersionFixed in Version6.3 
Summary0005811: segfault in libresolv-2.12.so whe upgrading to Centos6.3
Descriptionan upgrade from a working 6.2 system fails to start sendmail due to a segfault in libresolv-2.12.so

sendmail[6772]: segfault at 1 ip 00007fd047110596 sp 00007fff8954c440 error 6 in libresolv-2.12.so[7fd047104000+16000]
sendmail[6778]: segfault at 1 ip 00007fd405468596 sp 00007fff23642430 error 6 in libresolv-2.12.so[7fd40545c000+16000]
sendmail[6948]: segfault at 1 ip 00007f0054f15596 sp 00007fffaf4f5490 error 6 in libresolv-2.12.so[7f0054f09000+16000]
sendmail[6950]: segfault at 1 ip 00007f4ae2c11596 sp 00007fff7bc01c90 error 6 in libresolv-2.12.so[7f4ae2c05000+16000]
sendmail[7054]: segfault at 1 ip 00007ff363047596 sp 00007fff4823a070 error 6 in libresolv-2.12.so[7ff36303b000+16000]
sendmail[7060]: segfault at 1 ip 00007f833817f596 sp 00007fff8e59ad00 error 6 in libresolv-2.12.so[7f8338173000+16000]

Apparently, having IPv6 nameservers in /etc/resolv.conf causes this. it was not an issue in 6.2
Steps To Reproduceadd an IPv6 address in /etc/resolv.conf to use as a resolver and sendmail will not start;

/etc/rc.d/init.d/sendmail restart
Shutting down sm-client: [ OK ]
Shutting down sendmail: [ OK ]
Starting sendmail: /bin/bash: line 1: 7368 Segmentation fault /usr/sbin/sendmail -bd -q1h
Starting sm-client: /bin/bash: line 1: 7374 Segmentation fault /usr/sbin/sendmail -L sm-msp-queue -Ac -q1h

a segfault is logged to the dmesg.

by changing the DNS resolvers in /etc/resolv.conf to IPv4 addresses, sendmail starts correctly.
TagsNo tags attached.
related to 0005838closed range Exim cannot deliver or receive mails 
Attached Files

2012-07-09 22:43   
possibly https://bugzilla.redhat.com/show_bug.cgi?id=835090
2012-07-10 09:54   
Make sure that you only have IPv4 addresses in your /etc/resolv.conf (from the bug that tru posted)
2012-07-10 13:54   
indeed, with only IPv4 resolvers sendmail will start. As soon as even one of them is an IPv6 address, the segfault occurs. using IPv4 only for now
2012-07-11 08:34   
When using brackets, there is no problem.

[root@shell ~]# cat /etc/resolv.conf
; generated by /sbin/dhclient-script
search domain.tld
nameserver [2a01:1:b::c53]
nameserver [2a01:1:a::c53]
2012-07-11 13:42   
when using brackets, there is no problem as in the fact that nothing crashes; however, if you have _ONLY_ IPv6 resolver addresses, you can't resolve anything. You will note that if you remove your and IP addresses from your resolv.conf, the system no longer can resolve anything.
2012-07-14 20:27   
Commenting out the ipv6 nameservers using an ipv6 address helps.

2012-07-18 16:29   

* A programming error caused an internal array of nameservers to be only
partially initialized when the /etc/resolv.conf file contained IPv6
nameservers. Depending on the contents of a nearby structure, this could
cause certain applications to terminate unexpectedly with a segmentation
fault. The programming error has been fixed, which restores proper behavior
with IPv6 nameservers listed in the /etc/resolv.conf file. (BZ#837026)
2012-07-19 21:44   
I confirm that updating glibc-2.12-1.80.el6_3.3.i686 has fixed the issue
2012-07-19 22:04   
I activated the resolv.conf ipv6 nameservers after updating glibc and I can confirm that my issue is resolved too. It is working fine now.
2013-03-02 21:26   
marking as solved as per reporters feedback

Issue History
2012-07-09 22:30ronvachNew Issue
2012-07-09 22:43truNote Added: 0015380
2012-07-10 09:54JohnnyHughesNote Added: 0015385
2012-07-10 13:54ronvachNote Added: 0015387
2012-07-11 08:34randytenhaveNote Added: 0015397
2012-07-11 13:42ronvachNote Added: 0015403
2012-07-14 20:27vrotogelNote Added: 0015452
2012-07-14 23:27rangeRelationship addedrelated to 0005838
2012-07-18 16:29truNote Added: 0015499
2012-07-19 21:44ronvachNote Added: 0015515
2012-07-19 22:04vrotogelNote Added: 0015516
2013-03-02 21:26tigalchNote Added: 0016578
2013-03-02 21:26tigalchStatusnew => resolved
2013-03-02 21:26tigalchFixed in Version => 6.3
2013-03-02 21:26tigalchResolutionopen => fixed