Bug 1355650 (CVE-2016-6197)

Summary:	CVE-2016-6197 kernel: overlayfs: missing upper dentry verification before unlink and rename
Product:	[Other] Security Response	Reporter:	Martin Prpič <mprpic>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	aquini, arm-mgr, bhu, dhoward, fhrbata, gansalmon, iboverma, itamar, jforbes, jkacur, joelsmith, jonathan, jross, jwboyer, kernel-maint, kernel-mgr, kstutsma, lgoncalv, madhu.chinakonda, matt, mchehab, mcressma, nmurray, plougher, qcai, rt-maint, rvrbovsk, slawomir, williams, wmealing
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:	It was found that the unlink and rename functionality in overlayfs did not verify the upper dentry for staleness. A local, unprivileged user could use the rename syscall on overlayfs on top of xfs to panic or crash the system.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-08 02:56:11 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:	1258556, 1341795, 1355651, 1359019, 1359021, 1359022, 1359023, 1359024, 1359025, 1360155
Bug Blocks:	1355693

Description Martin Prpič 2016-07-12 07:26:15 UTC

It was found that the unlink and rename functionality in overlayfs did not verify the upper dentry for staleness. A local, unprivileged user could use the rename syscall on overlayfs on top of xfs to crash the system.

Upstream patch:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=11f3710417d026ea2f4fcf362d866342c5274185

CVE assignment:

http://seclists.org/oss-sec/2016/q3/42

Comment 1 Martin Prpič 2016-07-12 07:26:57 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1355651]

Comment 2 Martin Prpič 2016-07-12 14:01:08 UTC

Acknowledgments:

Name: CAI Qian (Red Hat)

Comment 3 Wade Mealing 2016-07-22 05:40:24 UTC

Statement: 

This issue is not present in the Linux kernel packages as shipped with Red Hat Enterprise Linux versions 5 and 6.

This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 7 and MRG-2. Future Linux kernel updates for the respective releases may address this issue.