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Bug 1324568

Summary: glibc: getent returns dud entry when nscd enabled
Product: Red Hat Enterprise Linux 7 Reporter: Martin Poole <mpoole>
Component: glibcAssignee: Florian Weimer <fweimer>
Status: CLOSED ERRATA QA Contact: Sergey Kolosov <skolosov>
Severity: medium Docs Contact: Vladimír Slávik <vslavik>
Priority: high    
Version: 7.2CC: alanm, anrussel, ashankar, codonell, cww, fweimer, mcermak, mnewsome, mpoole, pfrankli, skolosov, sreber, thomas.oulevey, vslavik
Target Milestone: rcKeywords: Patch, ZStream
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
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:
: 1436312 (view as bug list) Environment:
Last Closed: 2017-08-01 18:06:55 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:    
Bug Blocks: 1298243, 1390370, 1436312    
Attachments:
Description Flags
dns capture
none
copy of hosts db after bad lookup none

Description Martin Poole 2016-04-06 15:55:54 UTC
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 15:58:14 UTC
Created attachment 1144266 [details]
dns capture

Comment 3 Martin Poole 2016-04-06 15:58:59 UTC
Created attachment 1144267 [details]
copy of hosts db after bad lookup

Comment 9 Florian Weimer 2016-05-30 12:20:12 UTC
*** Bug 1339925 has been marked as a duplicate of this bug. ***

Comment 17 Thomas Oulevey 2017-02-21 08:41:14 UTC
Any news on a target release ?

Comment 18 Carlos O'Donell 2017-02-22 14:44:21 UTC
(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 12:16:49 UTC
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 18:06:55 UTC
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