Bug 710338 (CVE-2011-2183)

Summary:	CVE-2011-2183 kernel: ksm: race between ksmd and exiting task
Product:	[Other] Security Response	Reporter:	Eugene Teo (Security Response) <eteo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	arozansk, fhrbata, kernel-mgr, kmcmartin, lwang, nobody, pmatouse, qcui, sforsber, tcallawa
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-07-29 12:48:43 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:	710340, 710341, 710988
Bug Blocks:

Description Eugene Teo (Security Response) 2011-06-03 05:55:23 UTC

Andrea Righi reported a case where an exiting task can race against ksmd.  

ksm_scan.mm_slot == the only registered mm
CPU 1 (bug program)		CPU 2 (ksmd)
 				list_empty() is false
lock
ksm_scan.mm_slot
list_del
unlock
 				slot == &ksm_mm_head (but list is now empty_)

Close this race by revalidating that the new slot is not simply the list head again.

Reproducer: http://www.spinics.net/lists/linux-mm/msg20233.html
Proposed patch: http://www.spinics.net/lists/linux-mm/msg20301.html

Acknowledgements:

Red Hat would like to thank Andrea Righi for reporting this issue.

Comment 2 Eugene Teo (Security Response) 2011-06-03 06:03:50 UTC

Statement:

This issue did not affect the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 4, 5, and Red Hat Enterprise MRG do not provide support for KSM (Kernel Samepage Merging). This has been addressed in Red Hat Enterprise Linux 6 via https://rhn.redhat.com/errata/RHSA-2011-1189.html.

Comment 4 Chuck Ebbert 2011-06-23 09:24:46 UTC

Upstream commit:

 http://git.kernel.org/linus/2b472611a32a72f4a118c069c2d62a1a3f087afd

Comment 5 Eugene Teo (Security Response) 2011-07-06 08:41:00 UTC

*** Bug 719238 has been marked as a duplicate of this bug. ***

Comment 6 errata-xmlrpc 2011-08-23 14:42:24 UTC

This issue has been addressed in following products:

  Red Hat Enterprise Linux 6

Via RHSA-2011:1189 https://rhn.redhat.com/errata/RHSA-2011-1189.html

Comment 7 errata-xmlrpc 2011-09-12 19:45:36 UTC

This issue has been addressed in following products:

  MRG for RHEL-6 v.2

Via RHSA-2011:1253 https://rhn.redhat.com/errata/RHSA-2011-1253.html