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Bug 1452032

Summary: when the /etc/hosts file has a line longer than 1028 characters getent ahostsv4 and ahostsv6 will stop working.
Product: Red Hat Enterprise Linux 6 Reporter: Raul Mahiques <rmahique>
Component: glibcAssignee: glibc team <glibc-bugzilla>
Status: CLOSED WONTFIX QA Contact: qe-baseos-tools-bugs
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 6.9CC: ashankar, brubisch, cww, fweimer, mnewsome, pfrankli, rmahique
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1452034 (view as bug list) Environment:
Last Closed: 2017-08-16 16:18:26 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1452034    
Bug Blocks:    

Description Raul Mahiques 2017-05-18 08:12:16 UTC 
Description of problem:
when the /etc/hosts file has a line longer than 1028 characters getent ahostsv4 and ahostsv6 will stop working for hostsnames present in /etc/hosts.
This happens even if the line is a comment.

Version-Release number of selected component (if applicable):
Tested in RHEL 6.9 and RHEL 7.3
glibc-2.17-157
glibc-2.12-1

How reproducible:
Always




Steps to Reproduce:
With this oneliner you can see how it stops resolving after the line reaches 1028 characters, even if it's commented.
echo -n '#' >>/etc/hosts ; for i in $(seq 1 1030); do echo -n "$i - "; echo -n 'a' >>/etc/hosts ; getent ahostsv4 `hostname -f`; done


Actual results:
It stops working after 1028 characters.

Expected results:
It continues working and at least ignores the commented line

Additional info:
Comment 2 Florian Weimer 2017-05-18 08:20:10 UTC 
(In reply to Raul Mahiques from comment #0)
> Version-Release number of selected component (if applicable):
> Tested in RHEL 6.9 and RHEL 7.3
> glibc-2.17-157
> glibc-2.12-1
> 
> How reproducible:
> Always

Please provide the exact glibc versions where you reproduced this.  Thanks.
Comment 3 Raul Mahiques 2017-05-18 08:39:26 UTC 
I reproduced it on both versions.
note that the result of `hostname -f` must be present in /etc/hosts otherwise replace it with a hostname present in /etc/hosts.
Comment 4 Florian Weimer 2017-05-18 09:04:57 UTC 
(In reply to Raul Mahiques from comment #3)
> I reproduced it on both versions.
> note that the result of `hostname -f` must be present in /etc/hosts
> otherwise replace it with a hostname present in /etc/hosts.

Please post the output of “rpm -q glibc” and attach the final contents of /etc/hosts and /etc/nsswitch.conf.  Thanks.
Comment 5 Raul Mahiques 2017-05-18 09:35:41 UTC 
glibc-2.17-157.el7_3.1.x86_64


Final content
#aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa



/etc/nsswitch.conf
hosts:      files dns myhostname
Comment 8 Florian Weimer 2017-05-18 15:52:20 UTC 
Note: The use of `hostname -f` in the reproducer in comment #0 hides the presence of the issue in a default configuration.
Comment 11 Raul Mahiques 2017-05-29 08:37:54 UTC 
(In reply to Florian Weimer from comment #8)
> Note: The use of `hostname -f` in the reproducer in comment #0 hides the
> presence of the issue in a default configuration.

it does not if you have the FQDN in your /etc/hosts file.