Bug 1367814 (CVE-2015-8953)

Summary:	CVE-2015-8953 kernel: overlayfs: Double dentry reference leak in copy-up failure
Product:	[Other] Security Response	Reporter:	Adam Mariš <amaris>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	agordeev, anemec, aquini, bhu, dhoward, esammons, fhrbata, iboverma, jkacur, joelsmith, jross, kernel-mgr, lgoncalv, lwang, matt, mcressma, mguzik, nmurray, plougher, rvrbovsk, security-response-team, slawomir, vdronov, 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:	A flaw was found in the Linux kernel's implementation of overlayfs. An attacker can leak file resources in the system by opening a large file with write permissions on a overlay filesystem that is insufficient to deal with the size of the write. When unmounting the underlying device, the system is unable to free an inode and this will consume resources. Repeating this for all available inodes and memory will create a denial of service situation.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-11-04 18:43:44 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:	1370467
Bug Blocks:	1367816

Description Adam Mariš 2016-08-17 14:29:28 UTC

A flaw was found in the Linux kernels implementation of overlayfs.  An attacker can leak a file resources in the system by opening a large file with write permissions on a overlay filesystem that is insufficient to deal with the size of the write.

When unmounting the underlying device, the system is unable to free an inode and this will consume resources.  Repeating this for all available inodes and memory will create a denial of service situation.

Product bug:

https://bugzilla.redhat.com/show_bug.cgi?id=1261073

Upstream patch:

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ab79efab0a0ba01a74df782eb7fa44b044dae8b5

Comment 2 Andrej Nemec 2016-08-26 08:19:16 UTC

CVE assignment:

http://seclists.org/oss-sec/2016/q3/377

Comment 3 Andrej Nemec 2016-08-26 12:22:27 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1370467]

Comment 4 Wade Mealing 2016-10-04 02:49:32 UTC

Statement:

This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 6 as the code with the flaw is not present in the products listed.

This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux  7 and MRG-2. This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.

Comment 5 Wade Mealing 2016-10-04 02:53:40 UTC

Acknowledgements:

Name: CAI Qian (Red Hat Engineering)