Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Bug 1876525

Summary:	mod_fcgid does not pass more than 64 variables to an FCGI server process environment
Product:	Red Hat Enterprise Linux 8	Reporter:	Petr Pisar <ppisar>
Component:	mod_fcgid	Assignee:	Luboš Uhliarik <luhliari>
Status:	CLOSED ERRATA	QA Contact:	icesalov
Severity:	unspecified	Docs Contact:	Lenka Špačková <lkuprova>
Priority:	unspecified
Version:	8.2	CC:	bnater, icesalov, jorton, luhliari, mkyral, presharm
Target Milestone:	rc	Keywords:	AutoVerified, FutureFeature, Triaged
Target Release:	8.4	Flags:	pm-rhel: mirror+
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Enhancement
Doc Text:	.The `mod_fcgid` module can now pass up to 1024 environment variables to an FCGI server process With this update, the `mod_fcgid` module for the Apache HTTP Server can pass up to 1024 environment variables to a FastCGI (FCGI) server process. The previous limit of 64 environment variables could cause applications running on the FCGI server to malfunction.	Story Points:	---
Clone Of:
Clones:	1958882 (view as bug list)		Environment:
Last Closed:	2021-05-18 15:53:56 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:	1958882

Description Petr Pisar 2020-09-07 11:59:06 UTC

An OpenShift user noticed <https://github.com/sclorg/dancer-ex/issues/78#issuecomment-687849728> that mod_fcgid does not pass more than 64 environment variables into an FCGI server process. As a result an application running in the FCGI server is missing the variables and misbehaves:

[Sun Sep 06 17:28:04.722760 2020] [fcgid:warn] [pid 18:tid 281472258011088] [client 10.131.0.1:52618] mod_fcgid: 150 environment variables dropped; increase INITENV_CNT in fcgid_pm.h from 64 to at least 214
Can't locate Plack/Runner.pm in @INC (you may need to install the Plack::Runner module) (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at /opt/app-root/src/extlib/bin/plackup line 3.
BEGIN failed--compilation aborted at /opt/app-root/src/extlib/bin/plackup line 3.
[Sun Sep 06 17:28:04.733448 2020] [fcgid:warn] [pid 18:tid 281472258011088] (104)Connection reset by peer: [client 10.131.0.1:52618] mod_fcgid: error reading data from FastCGI server
[Sun Sep 06 17:28:04.733551 2020] [core:error] [pid 18:tid 281472258011088] [client 10.131.0.1:52618] End of script output before headers: health

See the first line. The user needs in this case to increase the limit to 214. I'm not sure what's the reasonable number, but I propose increasing it to 1024. The limit is built into a mod_fcgid httpd module. The fix needs patching mod_fcgid sources (INITENV_CNT macro in modules/fcgid/fcgid_conf.h).

You can adapt a reproducer from bug #1651310. But this time place more than 64 distinct FcgidInitialEnv directives to a mod_fcgid configuration and then compare them with the environment of the running FCGI server process.

Comment 1 Yaakov Selkowitz 2020-09-07 18:10:51 UTC

The 200+ variables were a result of attempting to deploy dancer-mysql-example template in a project in which other samples had been deployed (for general testing).  Retesting in a clean OpenShift project show 57 environment variables present.  So this does work right now, but requiring a pristine project isn't optimal, and there isn't much room for future environment growth either.

The patch which enabled longer environment variable values mentioned a cost in terms of struct size.  What would be the cost of significantly increasing INITENV_CNT?

Comment 2 Petr Pisar 2020-09-08 06:10:48 UTC

Each variable occupies 320 bytes. Increasing the number of variables from 64 to 1024 would mean 307200 B more memory used by each FCGI server process.

Comment 22 errata-xmlrpc 2021-05-18 15:53:56 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 (mod_fcgid 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/RHBA-2021:1880