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Bug 1998521 - sosreport can hang with a relative symlink loop
Summary: sosreport can hang with a relative symlink loop
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: sos
Version: 8.4
Hardware: All
OS: Linux
low
low
Target Milestone: rc
: ---
Assignee: Pavel Moravec
QA Contact: Miroslav Hradílek
URL:
Whiteboard:
Depends On:
Blocks: 2011533
TreeView+ depends on / blocked
 
Reported: 2021-08-27 13:14 UTC by Christophe Besson
Modified: 2024-10-01 19:13 UTC (History)
10 users (show)

Fixed In Version: sos-4.2-1.el8
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
: 2011533 (view as bug list)
Environment:
Last Closed: 2022-05-10 15:16:32 UTC
Type: Bug
Target Upstream Version:
Embargoed:
pm-rhel: mirror+

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Github sosreport sos pull 2664 0 None None None 2021-08-30 08:22:52 UTC
Red Hat Issue Tracker RHELPLAN-95428 0 None None None 2021-08-27 13:15:51 UTC
Red Hat Knowledge Base (Solution) 6289591 0 None None None 2021-08-30 08:33:11 UTC
Red Hat Product Errata RHEA-2022:1998 0 None None None 2022-05-10 15:16:58 UTC

Description Christophe Besson 2021-08-27 13:14:58 UTC 
Description of problem:
sosreport can hang with a relative symlink in /etc/alternatives.
Preventing this behaviour could help.

Version-Release number of selected component (if applicable):
sos-4.0-11.el8.noarch

How reproducible:
100%

Steps to Reproduce:
# mkdir -p /usr/lib/jvm/java-1.8.0-ibm-1.8.0.6.25-1jpp.1.el7.x86_64/jre/bin /usr/lib/jvm/java-1.8.0-ibm-1.8.0.6.25-1jpp.1.el7.x86_64/bin
# echo foobar > /usr/lib/jvm/java-1.8.0-ibm-1.8.0.6.25-1jpp.1.el7.x86_64/bin/javaws
# ln -s ../../bin/javaws /usr/lib/jvm/java-1.8.0-ibm-1.8.0.6.25-1jpp.1.el7.x86_64/jre/bin/javaws
# ln -s /usr/lib/jvm/java-1.8.0-ibm-1.8.0.6.25-1jpp.1.el7.x86_64/jre/bin/javaws /etc/alternatives/javaws
# ln -s /etc/alternatives/javaws /bin/javaws

Actual results:
[plugin:systemd] added cmd output 'timedatectl'
[plugin:systemd] skipped command 'systemd-resolve --status': required services missing: systemd-resolved. 
[plugin:systemd] skipped command 'systemd-resolve --statistics': required services missing: systemd-resolved. 
[plugin:systemd] added cmd output 'systemd-analyze plot'
[plugin:systemd] adding forbidden path '/dev/null'
[plugin:sysvipc] added cmd output 'ipcs'
[plugin:sysvipc] added cmd output 'ipcs -u'
[plugin:tuned] added cmd output 'tuned-adm list'
[plugin:tuned] added cmd output 'tuned-adm active'
[plugin:tuned] added cmd output 'tuned-adm recommend'
[plugin:tuned] added cmd output 'tuned-adm verify'
^C^C

Expected results:
No hang.

Additional info:
# cd /usr/lib/jvm/java-1.8.0-ibm-1.8.0.6.25-1jpp.1.el7.x86_64/jre/bin
# file $(readlink $(readlink $(readlink /bin/javaws)))
../../bin/javaws: ASCII text

# cd /tmp
# file $(readlink $(readlink $(readlink /bin/javaws)))
../../bin/javaws: symbolic link to `/etc/alternatives/javaws'

# grep -c readlink\(.*javaws /tmp/sos.strace
3644066

Note the issue also occurs on RHEL 7.
Comment 2 Pavel Moravec 2021-08-29 20:50:52 UTC 
There is a bug even in current upstream (which should affect also Fedora, imho). sos enters infinite loop in sos/report/plugins/unpackaged.py : 

            for root, dirs, files in os.walk(path, topdown=True):
                if exclude:
                    for e in exclude:
                        dirs[:] = [d for d in dirs if d not in e]
                for name in files:
                    path = os.path.join(root, name)
                    try:
                        while stat.S_ISLNK(os.lstat(path).st_mode):
                            path = os.path.abspath(os.readlink(path))


where the latest while cycle alters among:

/bin/javaws
/etc/alternatives/javaws
/usr/lib/jvm/java-1.8.0-ibm-1.8.0.6.25-1jpp.1.el7.x86_64/jre/bin/javaws
/bin/javaws
..


Simple solution imho:

                    from pathlib import Path
                    try:
                        while stat.S_ISLNK(os.lstat(path).st_mode):
                            path = Path(path).resolve()
                    except Exception:
                        continue

(I will think if it cant have a gotcha tomorrow)
Comment 3 Pavel Moravec 2021-08-29 21:07:29 UTC 
I forgot to mention an evident workaround: disable unpackaged plugin:

sos report -n unpackaged .. (other options)
Comment 6 Pavel Moravec 2022-01-04 22:32:54 UTC 
Hello,
would you be so kind to verify, if candidate build:

https://people.redhat.com/pmoravec/sos-4.2-8/

does fix the reported problem properly? We are on short with QE capacity and any help is more than welcomed.

(*ideally* verify it on both RHEL8 and RHEL9 (cloned bz2011533), but either verification is welcomed)
Comment 7 Christophe Besson 2022-01-12 10:06:49 UTC 
> does fix the reported problem properly? We are on short with QE capacity and any help is more than welcomed.

np, will do on el8 and el9 beta and will let you know.
Comment 8 Christophe Besson 2022-01-13 14:15:10 UTC 
Tested with the latest 4.2-8 on el8 and el9 beta and the issue does not appear anymore on both releases.
Comment 9 Christophe Besson 2022-01-13 14:15:59 UTC 
I forgot to mention I checked on the latest rhel 8.5.
Comment 12 errata-xmlrpc 2022-05-10 15:16:32 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 (sos bug fix and enhancement update), 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/RHEA-2022:1998
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