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Bug 1452032 - when the /etc/hosts file has a line longer than 1028 characters getent ahostsv4 and ahostsv6 will stop working.
Summary: when the /etc/hosts file has a line longer than 1028 characters getent ahosts...
Keywords:
Status: CLOSED WONTFIX
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: glibc
Version: 6.9
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: glibc team
QA Contact: qe-baseos-tools-bugs
URL:
Whiteboard:
Depends On: 1452034
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-05-18 08:12 UTC by Raul Mahiques
Modified: 2020-12-14 08:41 UTC (History)
7 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
: 1452034 (view as bug list)
Environment:
Last Closed: 2017-08-16 16:18:26 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Knowledge Base (Solution) 3047071 0 None None None 2017-05-22 13:48:22 UTC
Sourceware 21915 0 None None None 2019-01-08 15:20:27 UTC

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.
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