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Bug 161188

Summary:	Sometimes data/bss can be executable
Product:	Red Hat Enterprise Linux 3	Reporter:	Mark J. Cox <mjc>
Component:	kernel	Assignee:	Ingo Molnar <mingo>
Status:	CLOSED ERRATA	QA Contact:	Brian Brock <bbrock>
Severity:	high	Docs Contact:
Priority:	medium
Version:	3.0	CC:	davej, jbaron, peterm, petrides, tburke
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:	embargo=self,source=redhat,impact=important,reported=20050620
Fixed In Version:	RHSA-2006-0144	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2006-03-15 16:08:06 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:
Bug Depends On:
Bug Blocks:	168424

Description Mark J. Cox 2005-06-21 07:53:03 UTC

The execshield code in RHEL3 is pretty similar so this probably applies to RHEL3
as well; if so this is a serious issue (see #161136) 

+++ This bug was initially created as a clone of Bug #161136 +++

Whilst playing with an X application I found that around 20% of the time
libraries would get loaded between bss and brk, therefore making the
applications bss and data executable.  Ingo discovered it was due to an
execshield bug:

"this patch fixes the fallback randomizer to randomize between 
16MB...start_brk, instead of 16MB...brk. ->brk is problematic because 
due to brk randomization it creates a hole between BSS and brk, where 
DSOs might be loaded randomly." "i have tested the patch against the exec-shield
patch(es) in Fedora, so it would be safe to apply. PIEs work fine and the 
randomization now works correctly."

Comment 5 Ernie Petrides 2005-09-30 06:44:51 UTC

A fix for this problem has just been committed to the RHEL3 U7
patch pool this evening (in kernel version 2.4.21-37.4.EL).

Comment 8 Red Hat Bugzilla 2006-03-15 16:08:06 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 the 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/RHSA-2006-0144.html