Bug 1122472 (CVE-2014-5045)

Summary:	CVE-2014-5045 kernel: vfs: refcount issues during unmount on symlink
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, aquini, bhu, dhoward, esammons, fhrbata, gansalmon, iboverma, itamar, jforbes, jkacur, jonathan, jross, jwboyer, kernel-maint, kernel-mgr, lgoncalv, lwang, madhu.chinakonda, matt, mchehab, mcressma, nmurray, pholasek, plougher, rt-maint, rvrbovsk, vkrizan, vvs, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	A flaw was found in the way the Linux kernel's VFS subsystem handled reference counting when performing unmount operations on symbolic links. A local, unprivileged user could use this flaw to exhaust all available memory on the system or, potentially, trigger a use-after-free error, resulting in a system crash or privilege escalation.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-09-26 03:32:23 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:	1121323, 1122376, 1122480, 1122481, 1122482, 1135165
Bug Blocks:	1122485

Description Petr Matousek 2014-07-23 10:58:51 UTC

A flaw was found in the way reference counting was handled in the Linux kernel's
VFS subsystem when unmount on symlink was performed.

On Red Hat Enterprise Linux 6 an unprivileged local user could use this flaw to
cause OOM conditions leading to denial of service or, potentially, trigger
use-after-free error.

On Red Hat Enterprise Linux 7 a privileged local user with CAP_SYS_ADMIN
capability (also in a container) could use this flaw to cause OOM conditions
leading to denial of service or, potentially, trigger use-after-free error.

Acknowledgements:

Red Hat would like to thank Vasily Averin of Parallels for reporting this issue.

Comment 1 Petr Matousek 2014-07-23 11:12:15 UTC

Statement:

This issue does not affect Linux kernel packages as shipped with Red Hat
Enterprise Linux 5 and Red Hat Enterprise MRG 2.

Future Linux kernel updates for Red Hat Enterprise Linux 6 and 7 may address
this issue.

Comment 2 Petr Matousek 2014-07-23 11:13:38 UTC

Proposed upstream patch:

  https://lkml.org/lkml/2014/7/21/98

Comment 4 Petr Matousek 2014-07-23 11:21:09 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1122482]

Comment 5 Vasily Averin 2014-07-24 05:57:45 UTC

CVE-2014-5045 was assigned for this issue

Comment 6 Martin Prpič 2014-10-10 08:46:18 UTC

IssueDescription:

A flaw was found in the way the Linux kernel's VFS subsystem handled reference counting when performing unmount operations on symbolic links. A local, unprivileged user could use this flaw to exhaust all available memory on the system or, potentially, trigger a use-after-free error, resulting in a system crash or privilege escalation.

Comment 7 errata-xmlrpc 2014-10-14 06:19:40 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6

Via RHSA-2014:1392 https://rhn.redhat.com/errata/RHSA-2014-1392.html

Comment 9 errata-xmlrpc 2014-12-09 20:34:47 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2014:1971 https://rhn.redhat.com/errata/RHSA-2014-1971.html

Comment 10 errata-xmlrpc 2015-01-20 17:22:44 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6.5 EUS - Server and Compute Node Only

Via RHSA-2015:0062 https://rhn.redhat.com/errata/RHSA-2015-0062.html