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Bug 1320596

Summary:	glibc: NULL pointer dereference in stub resolver with unconnectable name server addresses
Product:	Red Hat Enterprise Linux 7	Reporter:	Florian Weimer <fweimer>
Component:	glibc	Assignee:	Florian Weimer <fweimer>
Status:	CLOSED ERRATA	QA Contact:	Michael Petlan <mpetlan>
Severity:	medium	Docs Contact:
Priority:	high
Version:	7.3	CC:	ashankar, bgollahe, codonell, fweimer, mcermak, mnewsome, mpetlan, pfrankli, redhat-bugzilla, tlavigne
Target Milestone:	rc	Keywords:	Patch, ZStream
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	No Doc Update
Doc Text:	undefined	Story Points:	---
Clone Of:	1316972
Clones:	1323839 (view as bug list)		Environment:
Last Closed:	2016-11-03 08:31:14 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:	1316972
Bug Blocks:	1323839
Deadline:	2016-03-31

Description Florian Weimer 2016-03-23 15:24:21 UTC

+++ This bug was initially created as a clone of Bug #1316972 +++

If /etc/resolv.conf contains addresses which cause the connect system call to fail immediately, queries which trigger search along the search path result in a segmentation fault.

A workaround is to remove the problematic addresses from /etc/resolv.conf.

--- Additional comment from Florian Weimer on 2016-03-23 16:22:08 CET ---

swbz#19825 is a very similar bug in send_vc/TCP (the original bug is about send_dg/UDP), so far only observed under valgrind.

swbz#19831 and swbz#19830 should be backported as well, to get cleaner test suite runs.

Comment 2 Florian Weimer 2016-03-31 08:23:26 UTC

Test case for the assert/NULL pointer dereference:

  https://pagure.io/glibc-resolv-tests/blob/master/f/tst-search2.c

Alternative test: Put “nameserver 255.255.255.255” as the first name server into /etc/resolv.conf, and run “getent ahosts does-not-exist”.  You need to have non-empty search path, too (“search redhat.com”, for example).

Comment 11 Michael Petlan 2016-08-04 14:15:39 UTC

Failed with glibc-2.17-105.el7 and passed with glibc-2.17-156.el7.

VERIFIED.

Comment 13 errata-xmlrpc 2016-11-03 08:31:14 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://rhn.redhat.com/errata/RHSA-2016-2573.html