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Bug 1636369

Summary: setroubleshootd dies while trying to clean up the signature database
Product: Red Hat Enterprise Linux 7 Reporter: Renaud Métrich <rmetrich>
Component: setroubleshootAssignee: Vit Mojzis <vmojzis>
Status: CLOSED ERRATA QA Contact: Milos Malik <mmalik>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.5CC: baitken, cww, jonathan.scott, lvrabec, mmalik, omosnace, plautrba
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: setroubleshoot-3.2.30-5.el7 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1695518 (view as bug list) Environment:
Last Closed: 2019-08-06 13:00:39 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: 1594286    

Description Renaud Métrich 2018-10-05 08:55:54 UTC
Description of problem:

Customer having tons of AVCs popping up regularly sees his setroubleshootd service die while updating the database:

-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot self.prune()
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot self.save()
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot Traceback (most recent call last):
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot self.delete_signature(sig, prune=True)"
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot File ""/usr/lib64/python2.7/site-packages/setroubleshoot/analyze.py"", line 377, in auto_save_callback"
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot File ""/usr/lib64/python2.7/site-packages/setroubleshoot/analyze.py"", line 355, in save"
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot File ""/usr/lib64/python2.7/site-packages/setroubleshoot/analyze.py"", line 320, in prune"
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot File ""/usr/lib64/python2.7/site-packages/setroubleshoot/analyze.py"", line 437, in delete_signature"
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot siginfo = self.lookup_signature(sig)
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot raise ProgramError(ERR_NO_SIGNATURE_MATCH)
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot File ""/usr/lib64/python2.7/site-packages/setroubleshoot/analyze.py"", line 399, in lookup_signature"
Oct  4 08:30:58 XXX org.fedoraproject.Setroubleshoot setroubleshoot.errcode.ProgramError: [Errno 1001] signature not found
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

This is due to multiple threads cleaning up the database concurrently, even though no locking mechanism is implemented in the daemon.


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

setroubleshoot-server-3.2.29-3.el7.x86_64


How reproducible:

Regularly on customer's site. Tried in my lab but failed for now (but tried not really hard).
A scenario is having more than max_alerts (50 by default) alerts in database, causing auto_save_callback to clean up the database.
While cleanup is happening, some new alert should be raised, causing another thread to perform the same cleanup.


Additional info:

After modifying the code to print out the Thread name (hack in log_debug(), util.py) and tuning log level to Debug, the customer hit the issue and analysis below shows clearly the concurrent modification of the database happening.

-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
import threading        <<< ADD THIS

def log_debug(msg):
    global log_level
    if log_level >= syslog.LOG_DEBUG:
        syslog.syslog(syslog.LOG_DEBUG, "Thread %s: %s" % (threading.currentThread().name, msg))             <<< AMEND THIS LINE
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

Analysis of occurrence:

MainThread does automatic saving of the database a 08:30:57, causing pruning of 80 alerts because number of alerts in database is greater than default max_alerts (50):

-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: writing database (/var/lib/setroubleshoot/setroubleshoot_database.xml) modified_count=194
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: auto_save database (/var/lib/setroubleshoot/setroubleshoot_database.xml) modified_count=194
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: lookup_signature: found 1 matches with scores 1.00
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: lookup_signature: found 1 matches with scores 1.00
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: delete_signature: sig=...
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: prune first 80 alerts, len(sigs=80 sigs=[...
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: delete_signature: sig=...
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: lookup_signature: found 1 matches with scores 1.00
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: lookup_signature: found 1 matches with scores 1.00
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: lookup_signature: found 1 matches with scores 1.00
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: delete_signature: sig=...
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: lookup_signature: found 1 matches with scores 1.00
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: delete_signature: sig=...
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: delete_signature: sig=...
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: delete_signature: sig=...
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: delete_signature: sig=...
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: lookup_signature: found 1 matches with scores 1.00
Oct  4 08:30:57 XXX setroubleshoot: Thread MainThread: writing database (/var/lib/setroubleshoot/setroubleshoot_database.xml) modified_count=201
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

At the same time Thread-1 wants to write to the database because a new AVC popped up:

-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
Oct  4 08:30:57 XXX setroubleshoot: Thread Thread-1: analyze_avc() avc=scontext=system_u:system_r:logrotate_t:s0-s0:c0.c1023 tcontext=system_u:object_r:udev_rules_t:s0 access=['getattr'] tclass=file tpath=/etc/udev/rules.d/70-persistent-ipoib.rules
Oct  4 08:30:57 XXX setroubleshoot: Thread Thread-1: lookup_signature: found 0 matches with scores
Oct  4 08:30:57 XXX setroubleshoot: Thread Thread-1: not in database yet
Oct  4 08:30:57 XXX setroubleshoot: Thread Thread-1: writing database (/var/lib/setroubleshoot/setroubleshoot_database.xml) modified_count=202
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

However, because too many alerts are in the database, Thread-1 also proceeded with the database cleanup:

-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
Oct  4 08:30:57 XXX setroubleshoot: Thread Thread-1: prune first 74 alerts, len(sigs=74 sigs=...
Oct  4 08:30:57 XXX setroubleshoot: Thread Thread-1: delete_signature: sig=...
Oct  4 08:30:57 XXX setroubleshoot: Thread Thread-1: lookup_signature: found 1 matches with scores 1.00
Oct  4 08:30:58 XXX setroubleshoot: Thread Thread-1: writing database (/var/lib/setroubleshoot/setroubleshoot_database.xml) modified_count=203
Oct  4 08:30:58 XXX setroubleshoot: Thread MainThread: delete_signature: sig=...
Oct  4 08:30:58 XXX setroubleshoot: Thread MainThread: lookup_signature: found 0 matches with scores
Oct  4 08:30:58 XXX setroubleshoot: Thread Thread-1: delete_signature: sig=...
...
Oct  4 08:30:58 XXX setroubleshoot: Thread Thread-1: delete_signature: sig=...
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

On the last line, setroubleshootd died due to the error above.

Comment 13 errata-xmlrpc 2019-08-06 13:00:39 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/RHBA-2019:2168