Bug 1321379

Summary: bash 4.1.2-33.el6_7.1 memory leak
Product: Red Hat Enterprise Linux 6 Reporter: Matt Kandoll <voidmaterial>
Component: bashAssignee: Siteshwar Vashisht <svashisht>
Status: CLOSED DUPLICATE QA Contact: BaseOS QE - Apps <qe-baseos-apps>
Severity: low Docs Contact:
Priority: unspecified    
Version: 6.7CC: sobolev
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-12-21 05:47:53 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:

Description Matt Kandoll 2016-03-25 23:39:35 UTC 
Description of problem:
Bash script memory utilization continually increases if bash internal pattern matching / substitution is used.

Version-Release number of selected component (if applicable):
[root@RHEL6-TEST mkandoll]# rpm -qi bash
Name        : bash                         Relocations: (not relocatable)
Version     : 4.1.2                             Vendor: Red Hat, Inc.
Release     : 33.el6_7.1                    Build Date: Mon 17 Aug 2015 03:51:51
Install Date: Fri 25 Mar 2016 04:26:05 PM MST      Build Host: x86-027.build.eng
Group       : System Environment/Shells     Source RPM: bash-4.1.2-33.el6_7.1.sr
Size        : 3142151                          License: GPLv3+
Signature   : RSA/8, Thu 20 Aug 2015 08:01:55 AM MST, Key ID 199e2f91fd431d51
Packager    : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
URL         : http://www.gnu.org/software/bash
Summary     : The GNU Bourne Again shell


How reproducible:
Every time

Steps to Reproduce:
Reproduced using script:
[root@RHEL6-BASIC mkandoll]# cat test17.sh
#!/bin/bash

while /bin/true
do

        test="something1234"
        test=${test//[^a-zA-Z0-9_.]/}

done

Run script for some time using:
nohup ./test17.sh 2>&1 > /dev/null &

Watch using top.

Actual results:
Memory usage increases without bound.

Expected results:
Memory is allocated first time and saved for reuse later.

Additional info:
Reproduced on a test vm using Red Hat Enterprise Linux Server release 6.5 (Santiago) that I upgraded bash package to 33.el6_7.1.  Seeing this in production servers running Red Hat Enterprise Linux Server release 6.7 (Santiago).
Testing is not possible on production servers.

For a workaround I am rewriting scripts that utilize this specific substitution to use echo piped to tr.
Comment 2 sobolev 2016-03-28 11:31:17 UTC 
Fixed in RHEL7 (BZ#1172214) - "Bash made a system call to allocate memory twice for the same purpose, which caused Bash to leak memory."
Patch (really stupid bug in bash 4.0-4.2):
--- bash-4.1/subst.c    2015-04-07 10:00:00.482931289 +0900
+++ bash-4.1/subst.c    2015-04-07 10:01:28.258111134 +0900
@@ -7039,8 +7039,6 @@

       ret = alloc_word_desc ();
       ret->word = temp1;
-      ret = alloc_word_desc ();
-      ret->word = temp1;
       if (temp1 && QUOTED_NULL (temp1) && (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)))
        ret->flags |= W_QUOTED|W_HASQUOTEDNULL;
       return ret;

But RHEL6 still needs the patches applied.
Comment 3 sobolev 2016-08-15 10:21:25 UTC 
Fixed in 4.1.2-35 (#1207042)
Maybe change status to resolved/fixed?
Comment 5 Siteshwar Vashisht 2016-12-21 05:47:53 UTC 

*** This bug has been marked as a duplicate of bug 1207042 ***