Bug 888271

Summary: snmpd should be careful about dlmod'ed modules when reloading configuration
Product: Red Hat Enterprise Linux 5 Reporter: Jan Pokorný [poki] <jpokorny>
Component: net-snmpAssignee: Jan Safranek <jsafrane>
Status: CLOSED NOTABUG QA Contact: BaseOS QE Security Team <qe-baseos-security>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 5.9   
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
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Fixed In Version: Doc Type: Bug Fix
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Clone Of:
: 888275 (view as bug list) Environment:
Last Closed: 2013-03-12 11:54:56 UTC Type: Bug
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On:    
Bug Blocks: 888275    

Description Jan Pokorný [poki] 2012-12-18 12:26:53 UTC 
Investigation of [bug 847289] showed snmpd is not careful about dynamic
modules when it comes to reloading the configuration (such as upon
receiving SIGHUP).

Dynamic modules seems to be loaded anew, which may corrupt previous
instances, avoid a proper cleanup actions and the like.
As per Jan Safranek, there is a room for improvement and less
error-prone behavior.
Comment 1 Jan Safranek 2012-12-18 12:32:15 UTC 
snmpd should not call init_<modulename> when the module is already loaded.

This implies that snmpd never reloads modules and the only way to update a module is to restart snmpd.
Comment 2 Jan Pokorný [poki] 2012-12-18 15:25:04 UTC 
Sorry for the noise, I came to the conclusion the current behavior is
OK and the limitation + solution are known [1].

Unless there is another issue with the current state, I would prefer
it as a status quo (maybe a sanity check at other dynamic modules we
provide should be performed -- generally, unregister registered MIBs
and registered alarms in deinit_<module> function).

[1] http://www.net-snmp.org/wiki/index.php/TUT:Writing_a_Dynamically_Loadable_Object#Initialization
Comment 3 Jan Pokorný [poki] 2012-12-20 13:32:14 UTC 
FWIW, there seem to be much more issues with reloading snmpd,
see, e.g., [2, 3].

[2] http://sourceforge.net/p/net-snmp/patches/1244/
[3] http://sourceforge.net/p/net-snmp/patches/1131/
Comment 4 Jan Safranek 2013-03-12 11:54:56 UTC 
Link [1] shows that it's module responsibility to track its init_ calls, I'm closing this bug.