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Bug 161188 - Sometimes data/bss can be executable
Summary: Sometimes data/bss can be executable
Alias: None
Product: Red Hat Enterprise Linux 3
Classification: Red Hat
Component: kernel
Version: 3.0
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Ingo Molnar
QA Contact: Brian Brock
Whiteboard: embargo=self,source=redhat,impact=imp...
Depends On:
Blocks: 168424
TreeView+ depends on / blocked
Reported: 2005-06-21 07:53 UTC by Mark J. Cox
Modified: 2007-11-30 22:07 UTC (History)
5 users (show)

Fixed In Version: RHSA-2006-0144
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2006-03-15 16:08:06 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2006:0144 qe-ready SHIPPED_LIVE Moderate: Updated kernel packages available for Red Hat Enterprise Linux 3 Update 7 2006-03-15 05:00:00 UTC

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.

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