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0005811CentOS-6sendmailpublic2012-07-09 22:302013-03-02 21:26
Reporterronvach 
PrioritynormalSeveritycrashReproducibilityalways
StatusresolvedResolutionfixed 
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
                                                           [FAILED]
Starting sm-client: /bin/bash: line 1: 7374 Segmentation fault /usr/sbin/sendmail -L sm-msp-queue -Ac -q1h
                                                           [FAILED]

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

Notes
(0015380)
tru   
2012-07-09 22:43   
possibly https://bugzilla.redhat.com/show_bug.cgi?id=835090
(0015385)
JohnnyHughes   
2012-07-10 09:54   
Make sure that you only have IPv4 addresses in your /etc/resolv.conf (from the bug that tru posted)
(0015387)
ronvach   
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
(0015397)
randytenhave   
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 11.22.33.44
nameserver 55.66.77.88
nameserver [2a01:1:b::c53]
nameserver [2a01:1:a::c53]
(0015403)
ronvach   
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 11.22.33.44 and 55.66.77.88 IP addresses from your resolv.conf, the system no longer can resolve anything.
(0015452)
vrotogel   
2012-07-14 20:27   
Commenting out the ipv6 nameservers using an ipv6 address helps.

Thanks.
(0015499)
tru   
2012-07-18 16:29   
https://rhn.redhat.com/errata/RHSA-2012-1098.html

* 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)
(0015515)
ronvach   
2012-07-19 21:44   
I confirm that updating glibc-2.12-1.80.el6_3.3.i686 has fixed the issue
(0015516)
vrotogel   
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.
(0016578)
tigalch   
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