Bug 460692

Summary: m2crypto leaks fds into GC
Product: Red Hat Enterprise Linux 5 Reporter: James Antill <james.antill>
Component: m2cryptoAssignee: Miloslav Trmač <mitr>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: 5.3CC: apevec, charles_duffy, ctatman, james.antill, jfeeney, ohudlick, sgrubb, wwlinuxengineering, zmraz
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2009-09-02 11:19:56 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
Patch against 0.19.1 - applies against the RHEL5 version as well none

Description James Antill 2008-08-29 18:35:58 UTC 
Description of problem:

 This is basically a copy and paste of the problem from urllib2:

http://bugs.python.org/issue3066

...in m2urllib2, you do:

        r.recv = r.read

...which creates a circular reference, I've tested the fix I posted in m2crypto and it seems to work (although I'm not convinced it's the best fix).

 This would be nice to fix for 5.3.
Comment 1 Miloslav Trmač 2008-09-01 21:32:18 UTC 
Thanks for your report.

Does the leak have any noticeable user impact?
Comment 2 Charles Duffy 2008-09-01 21:37:18 UTC 
Yes; using reposync (from yum-utils) it is possible to overrun the 1024 FDs allowed by default ulimit settings and crash the process.
Comment 3 James Antill 2008-09-05 01:02:40 UTC 
 It's worth noting that the generic fix has gone into the 5.3 errata, so putting it into m2crypto wouldn't be a deviation from core python urllib2 in RHEL-5.
Comment 5 Miloslav Trmač 2009-02-04 17:43:34 UTC 
Reproducer for M2Crypto:

import gc
import M2Crypto
o = M2Crypto.m2urllib2.build_opener()
r = o.open('https://addons.mozilla.org')
s = [r.fp._sock.fp._sock]
r.close()
print gc.get_referrers(s[0])
... should print only [[<M2Crypto.SSL.Connection.Connection instance ... >]],
    not including a <socket._fileobject> instance

Upstream urllib2 solves this by ignoring the circular reference, and explicitly disconnecting r.fp from r on r.close(): see http://svn.python.org/view/python/trunk/Lib/urllib2.py?rev=53511&r1=52481&r2=53511 .  This drops other references and eventually closes the underlying socket - but only if the user of "r" calls r.close() on it.

AFAICS reposync uses urlgrab, which always calls r.close().
Comment 6 Miloslav Trmač 2009-02-04 19:17:11 UTC 
Created attachment 330905 [details]
Patch against 0.19.1 - applies against the RHEL5 version as well

The attached patch will be available in rawhide m2crypto-0.19.1-5.

Can you test the patch in the scenario where the circular reference actually causes problems, please?
Comment 11 errata-xmlrpc 2009-09-02 11:19:56 UTC 
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2009-1351.html