Bug 499548

Summary: kernel: proc: avoid information leaks to non-privileged processes [rhel-4.9]
Product: Red Hat Enterprise Linux 4 Reporter: Eugene Teo (Security Response) <eteo>
Component: kernelAssignee: Cong Wang <amwang>
Status: CLOSED ERRATA QA Contact: Evan McNabb <emcnabb>
Severity: high Docs Contact:
Priority: high    
Version: 4.9CC: lwang, rkhan, security-response-team, sghosh, syeghiay, vgoyal
Target Milestone: rcKeywords: ZStream
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: 499541 Environment:
Last Closed: 2011-02-16 15:48:11 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: 499541    
Bug Blocks:    

Description Eugene Teo (Security Response) 2009-05-07 06:19:00 UTC 
+++ This bug was initially created as a clone of Bug #499541 +++

Description of problem:
By using the same test as is used for /proc/pid/maps and /proc/pid/smaps, only allow processes that can ptrace() a given process to see information that might be used to bypass address space layout randomization (ASLR). These include eip, esp, wchan, and start_stack in /proc/pid/stat as well as the non-symbolic output from /proc/pid/wchan.

ASLR can be bypassed by sampling eip as shown by the proof-of-concept code at http://code.google.com/p/fuzzyaslr/ As part of a presentation (http://www.cr0.org/paper/to-jt-linux-alsr-leak.pdf) esp and wchan were also noted as possibly usable information leaks as well.  The start_stack address also leaks potentially useful information.

Upstream commit: http://git.kernel.org/linus/f83ce3e6b02d5e48b3a43b001390e2b58820389d

--- Additional comment from eteo on 2009-05-07 02:09:48 EDT ---

Created an attachment (id=342773)
Upstream patch
Comment 1 Eugene Teo (Security Response) 2009-05-13 09:23:51 UTC 
Wang Cong, remember to change the status after posting the patch to rhkl. Thanks.
Comment 2 Vivek Goyal 2009-06-03 13:57:22 UTC 
Committed in 89.2.EL
Comment 5 errata-xmlrpc 2011-02-16 15:48:11 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 therefore 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-2011-0263.html