Bug 803793 (CVE-2012-1179)

Summary:	CVE-2012-1179 kernel: thp:__split_huge_page() mapcount != page_mapcount BUG_ON()
Product:	[Other] Security Response	Reporter:	Petr Matousek <pmatouse>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	agordeev, anton, arozansk, bhu, davej, dhoward, fhrbata, gansalmon, itamar, jkacur, jonathan, jwboyer, kernel-maint, kernel-mgr, lgoncalv, lwang, madhu.chinakonda, plougher, rt-maint, sforsber, williams
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:	2013-08-24 12:26:33 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:	800328, 803808, 803809, 823612, 1165268, 1188485, 1188486, 1188487, 1188488
Bug Blocks:	802633

Description Petr Matousek 2012-03-15 16:36:45 UTC

In some cases it may happen that pmd_none_or_clear_bad() is called
with the mmap_sem hold in read mode. In those cases the huge page
faults can allocate hugepmds under pmd_none_or_clear_bad() and that
can trigger a false positive from pmd_bad() that will not like to see
a pmd materializing as trans huge.

A privileged user in the KVM guest can use this flaw to crash the host.
An unprivileged local user could use this flaw to crash the system.

Proposed upstream patch:
http://comments.gmane.org/gmane.linux.kernel.mm/75413

Comment 2 Petr Matousek 2012-03-15 16:57:20 UTC

Created kernel tracking bugs for this issue

Affects: fedora-all [bug 803809]

Comment 4 Fedora Update System 2012-03-17 23:58:33 UTC

kernel-3.2.10-3.fc16 has been pushed to the Fedora 16 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 5 Fedora Update System 2012-03-26 18:02:11 UTC

kernel-2.6.42.12-1.fc15 has been pushed to the Fedora 15 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 7 Petr Matousek 2012-05-24 18:07:42 UTC

Upstream fix:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=1a5a9906d4e8d1976b701f889d8f35d54b928f25

Comment 8 errata-xmlrpc 2012-06-18 13:33:45 UTC

This issue has been addressed in following products:

  Red Hat Enterprise Linux 6

Via RHSA-2012:0743 https://rhn.redhat.com/errata/RHSA-2012-0743.html

Comment 9 errata-xmlrpc 2012-06-26 18:43:36 UTC

This issue has been addressed in following products:

  Red Hat Enterprise Linux 6.1 EUS - Server Only

Via RHSA-2012:1042 https://rhn.redhat.com/errata/RHSA-2012-1042.html