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Bug 499541

Summary: kernel: proc: avoid information leaks to non-privileged processes [rhel-5.4]
Product: Red Hat Enterprise Linux 5 Reporter: Eugene Teo (Security Response) <eteo>
Component: kernelAssignee: Cong Wang <amwang>
Status: CLOSED ERRATA QA Contact: Red Hat Kernel QE team <kernel-qe>
Severity: high Docs Contact:
Priority: urgent    
Version: 5.4CC: dhoward, dzickus, emcnabb, jpirko, jplans, lwang, onestero, rkhan, security-response-team, syeghiay, vmayatsk
Target Milestone: rcKeywords: ZStream
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 499546 499548 499549 499550 (view as bug list) Environment:
Last Closed: 2009-09-02 08:02:33 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: 499546, 499548, 499549, 499550    
Attachments:
Description Flags
Upstream patch none

Description Eugene Teo (Security Response) 2009-05-07 06:04:16 UTC 
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
Comment 1 Eugene Teo (Security Response) 2009-05-07 06:09:48 UTC 
Created attachment 342773 [details]
Upstream patch
Comment 3 RHEL Program Management 2009-05-11 20:59:36 UTC 
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.
Comment 5 Don Zickus 2009-06-04 16:07:28 UTC 
in kernel-2.6.18-152.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Please do NOT transition this bugzilla state to VERIFIED until our QE team
has sent specific instructions indicating when to do so.  However feel free
to provide a comment indicating that this fix has been verified.
Comment 9 errata-xmlrpc 2009-09-02 08:02:33 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-2009-1243.html