Bug 1646373

Summary: glibc: Crash in getaddrinfo_a when thread creation fails
Product: Red Hat Enterprise Linux 7 Reporter: Florian Weimer <fweimer>
Component: glibcAssignee: DJ Delorie <dj>
Status: CLOSED ERRATA QA Contact: qe-baseos-tools-bugs
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 7.7CC: ashankar, codonell, dj, fweimer, mnewsome, pfrankli, skolosov
Target Milestone: rcKeywords: Patch
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: glibc-2.17-269.el7 Doc Type: No Doc Update
Doc Text:
Story Points: ---
Clone Of:
: 1646379 1646381 (view as bug list) Environment:
Last Closed: 2019-08-06 12:49:05 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: 1646379, 1646381    
Bug Blocks: 1660844    

Description Florian Weimer 2018-11-05 13:29:25 UTC 
From the upstream bug report:

At line 237 in gai_misc.c:

lastp = requests_tail;
if (requests_tail == NULL)
  requests = requests_tail = newp;
else ...

If requests_tail was NULL then lastp remains NULL. 
Unfortunately if gai_create_helper_thread fails, lastp is de-referenced at line 267 which will cause a SIGSEGV.
Comment 1 Florian Weimer 2018-11-05 13:30:00 UTC 
This should be reproducible with a custom malloc which fails after the right number of allocations.
Comment 3 Florian Weimer 2018-11-05 13:54:12 UTC 
Upstream commit:

commit bd3b0fbae33a9a4cc5e2daf049443d5cf03d4251
Author: Andreas Schwab <schwab>
Date:   Mon Nov 5 12:47:30 2018 +0100

    libanl: properly cleanup if first helper thread creation failed (bug 22927)
Comment 6 Sergey Kolosov 2019-06-27 09:45:08 UTC 
Verified with modified __gai_create_helper_thread() function which always returns -1 and a test that calls getaddrinfo_a(). In glibc-2.17-269.el7 getaddrinfo_a() doesn't crash but returns EAGAIN.
Comment 9 errata-xmlrpc 2019-08-06 12:49:05 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-2019:2118