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Bug 1755154 - postgresql-libs - Deadlocks occur when using SSL in a multi-threaded environment
Summary: postgresql-libs - Deadlocks occur when using SSL in a multi-threaded environment
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: postgresql
Version: 7.7
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Patrik Novotný
QA Contact: Vaclav Danek
URL:
Whiteboard:
Depends On:
Blocks: 1716961
TreeView+ depends on / blocked
 
Reported: 2019-09-24 21:42 UTC by Matt Prahl
Modified: 2020-03-31 20:11 UTC (History)
7 users (show)

Fixed In Version:
Doc Type: No Doc Update
Doc Text:
Clone Of:
Environment:
Last Closed: 2020-03-31 20:11:03 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
A patch based on the upstream patch that resolves the issue (1.42 KB, patch)
2019-09-24 21:42 UTC, Matt Prahl 		no flags Details | Diff
A video showing the deadlock using the Python reproducer script (585.16 KB, video/webm)
2019-10-25 13:54 UTC, Matt Prahl 		no flags Details
A modified version of the reproducer Python 2 script (1.70 KB, text/x-python)
2019-10-25 13:58 UTC, Matt Prahl 		no flags Details
View All


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2020:1182 0 None None None 2020-03-31 20:11:06 UTC

Description Matt Prahl 2019-09-24 21:42:30 UTC 
Created attachment 1618713 [details]
A patch based on the upstream patch that resolves the issue

Description of problem:

A deadlock occurs when connecting to Postgresql using SSL with postgresql-libs in a multi-threaded environment with other threads performing SSL independently. This issue has been causing Module Build Service (https://pagure.io/fm-orchestrator) outages, which is deployed on RHEL 7.4 but with the latest postgresql-libs package installed.

You can find a reproducer script and a more in-depth description of the issue here:
https://postgrespro.com/list/thread-id/1861629

The upstream patch that resolves this issue is here:
https://commitfest.postgresql.org/4/140/

The patch does not apply cleanly, but I attached a patch that worked for our team.


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

postgresql-libs-9.2.24-1.el7_5.x86_64


How reproducible:

Easily reproducible. See the reproducer script in this upstream discussion:
https://postgrespro.com/list/thread-id/1861629


Actual results:

A deadlock occasionally occurs.


Expected results:

A deadlock does not occur.
Comment 4 Filip Januš 2019-10-25 13:01:28 UTC 
Hi,
I was trying to reproduce this bug on various version of RHEL(7.4,7.7,7.8) by using attached reproducer, but I am not able to attain deadlock. Are you able to add here Your configuration? (openssl package version and pg_hba.conf).
Comment 5 Matt Prahl 2019-10-25 13:54:32 UTC 
Created attachment 1629194 [details]
A video showing the deadlock using the Python reproducer script
Comment 6 Matt Prahl 2019-10-25 13:58:14 UTC 
Created attachment 1629195 [details]
A modified version of the reproducer Python 2 script
Comment 7 Matt Prahl 2019-10-25 14:40:09 UTC 
Hi Filip,
I attached a short video that shows the deadlock and I attached a slightly modified version of the Python 2 reproducer script that I used. It usually takes less than a couple of minutes for the deadlock to occur, but it took only a few seconds in the video I shared.

We are currently using openssl-1.0.2k-16.el7_6.1.x86_64 on the server that ran the reproducer script and on the server with Postgresql. As for the contents of pg_hba.conf, there is nothing special. We have one `hostssl` entry for MBS to connect to using a password.
Comment 8 Filip Januš 2019-10-29 15:09:28 UTC 
Hi,
thank You for Your advise but still I am not able to reproduce it. But I applied attached patch and build package. Here you can download it: http://download.eng.bos.redhat.com/brewroot/work/tasks/7480/24307480/postgresql-libs-9.2.24-2.el7_7.x86_64.rpm . Please are you able to test if deadlock occur after install new package?
Comment 9 Matt Prahl 2019-10-29 18:41:47 UTC 
Hi Filip,
That RPM installed fine and I can't reproduce the deadlock with it.
Comment 11 Matt Prahl 2019-10-30 14:06:13 UTC 
Filip what environment do you have setup for testing the reproducer script?
Comment 12 Matt Prahl 2019-10-30 15:58:42 UTC 
Filip, I created an environment using docker-compose that reproduces the issue. Please see the following repository:
https://github.com/mprahl/rhbz1755154-reproducer
Comment 20 errata-xmlrpc 2020-03-31 20:11:03 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-2020:1182
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