Bug 1324568 – glibc: getent returns dud entry when nscd enabled

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Bug 1324568 - glibc: getent returns dud entry when nscd enabled

Summary:	glibc: getent returns dud entry when nscd enabled

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	glibc (Show other bugs)
Sub Component:
Version:	7.2
Hardware:	Unspecified Unspecified

Priority	high Severity medium
Target Milestone:	rc
Target Release:	---
Assigned To:	Florian Weimer
QA Contact:	Sergey Kolosov
Docs Contact:	Vladimír Slávik

URL:
Whiteboard:
Keywords:	Patch, ZStream

Duplicates:	1339925 (view as bug list)
Depends On:
Blocks:	1298243 1390370 1436312
	Show dependency tree / graph

Reported:	2016-04-06 11:55 EDT by Martin Poole
Modified:	2017-08-01 14:06 EDT (History)
CC List:	14 users (show)

See Also:	1223095
Fixed In Version:	glibc-2.17-165.el7
Doc Type:	Bug Fix
Doc Text:	getaddrinfo no longer accessing uninitialised data On systems with the nscd daemon enabled, the `getaddrinfo()` function in the glibc library could access uninitialized data and consequently could return false address information. This update prevents uninitialized data access and ensures that correct addresses are returned.
Story Points:	---
Clone Of:
Clones:	1436312 (view as bug list)
Environment:
Last Closed:	2017-08-01 14:06:55 EDT
Type:	Bug
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
dns capture (772 bytes, application/octet-stream) 2016-04-06 11:58 EDT, Martin Poole	no flags	Details
copy of hosts db after bad lookup (401 bytes, application/x-gzip) 2016-04-06 11:58 EDT, Martin Poole	no flags	Details
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Sourceware	16743	None	None	None	2016-04-06 16:55 EDT
Red Hat Knowledge Base (Solution)	2345361	None	None	None	2016-05-30 11:24 EDT
Red Hat Product Errata	RHSA-2017:1916	normal	SHIPPED_LIVE	Moderate: glibc security, bug fix, and enhancement update	2017-08-01 14:05:43 EDT

Groups: None (edit)

Description Martin Poole 2016-04-06 11:55:54 EDT

Description of problem:

getent ahostsv4 www.google.com
216.58.213.132  STREAM www.google.com
216.58.213.132  DGRAM
216.58.213.132  RAW
(null)          STREAM
(null)          DGRAM
(null)          RAW



Version-Release number of selected component (if applicable):

glibc-2.17-106.el7_2.4.x86_64

How reproducible:

mostly

Steps to Reproduce:
1. ensure upstream nameserver does not have cached result.
2. systemctl stop nscd ; rm -f /var/db/nscd/hosts ; nscd -i hosts ; systemctl start nscd
3. getent ahostsv4 www.google.com


Actual results:

getent ahostsv4 www.google.com
216.58.213.132  STREAM www.google.com
216.58.213.132  DGRAM
216.58.213.132  RAW
(null)          STREAM
(null)          DGRAM
(null)          RAW

or a multiple response

64.15.112.44    STREAM www.google.com
64.15.112.44    DGRAM
64.15.112.44    RAW
64.15.112.55    STREAM
64.15.112.55    DGRAM
64.15.112.55    RAW
64.15.112.40    STREAM
64.15.112.40    DGRAM
64.15.112.40    RAW
64.15.112.25    STREAM
64.15.112.25    DGRAM
64.15.112.25    RAW
64.15.112.49    STREAM
64.15.112.49    DGRAM
64.15.112.49    RAW
64.15.112.50    STREAM
64.15.112.50    DGRAM
64.15.112.50    RAW
64.15.112.39    STREAM
64.15.112.39    DGRAM
64.15.112.39    RAW
64.15.112.24    STREAM
64.15.112.24    DGRAM
64.15.112.24    RAW
64.15.112.34    STREAM
64.15.112.34    DGRAM
64.15.112.34    RAW
64.15.112.59    STREAM
64.15.112.59    DGRAM
64.15.112.59    RAW
64.15.112.54    STREAM
64.15.112.54    DGRAM
64.15.112.54    RAW
64.15.112.30    STREAM
64.15.112.30    DGRAM
64.15.112.30    RAW
64.15.112.45    STREAM
64.15.112.45    DGRAM
64.15.112.45    RAW
64.15.112.35    STREAM
64.15.112.35    DGRAM
64.15.112.35    RAW
64.15.112.29    STREAM
64.15.112.29    DGRAM
64.15.112.29    RAW
64.15.112.20    STREAM
64.15.112.20    DGRAM
64.15.112.20    RAW
(null)          STREAM
(null)          DGRAM
(null)          RAW


Expected results:

getent ahostsv4 www.google.com
216.58.213.132  STREAM www.google.com
216.58.213.132  DGRAM
216.58.213.132  RAW


Additional info:

A hack of the getent source indicates that the call to inet_ntop is failing (return code not checked), printing the error gives

  inet_ntop FAILED 97/Address family not supported by protocol

where the address family is some garbage value.

Capturing the DNS traffic confirms that there is only the normal A & AAAA queries with valid replies.

Comment 2 Martin Poole 2016-04-06 11:58 EDT

Created attachment 1144266 [details]
dns capture

Comment 3 Martin Poole 2016-04-06 11:58 EDT

Created attachment 1144267 [details]
copy of hosts db after bad lookup

Comment 9 Florian Weimer 2016-05-30 08:20:12 EDT

*** Bug 1339925 has been marked as a duplicate of this bug. ***

Comment 17 Thomas Oulevey 2017-02-21 03:41:14 EST

Any news on a target release ?

Comment 18 Carlos O'Donell 2017-02-22 09:44:21 EST

(In reply to Thomas Oulevey from comment #17)
> Any news on a target release ?

The intent is to fix this for the upcoming RHEL 7.4. This is not a guarantee though. Thank you for your patience.

Comment 22 Florian Weimer 2017-03-02 07:16:49 EST

These unsupported and untested glibc preview builds contain a fix for this issue:

  https://copr.fedorainfracloud.org/coprs/fweimer/glibc-rhel-7.4/

Comment 35 errata-xmlrpc 2017-08-01 14:06:55 EDT

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2017:1916

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