Bug 1323577 (CVE-2015-8839)

Summary:	CVE-2015-8839 kernel: ext4 filesystem page fault race condition with fallocate call.
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
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, blc, dhoward, fhrbata, gansalmon, iboverma, itamar, jforbes, jkacur, joelsmith, jonathan, jross, jwboyer, kernel-maint, kernel-mgr, kstutsma, lgoncalv, madhu.chinakonda, matt, mchehab, mcressma, mlangsdo, nmurray, plougher, rt-maint, rvrbovsk, slawomir, vgoyal, williams, wmealing
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 Linux kernel when attempting to "punch a hole" in files existing on an ext4 filesystem. When punching holes into a file races with the page fault of the same area, it is possible that freed blocks remain referenced from page cache pages mapped to process' address space.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-08 02:50:13 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:	1323579, 1328705
Bug Blocks:	1323581

Description Andrej Nemec 2016-04-04 07:28:14 UTC

A flaw was found in the Linux kernel when attempting to "punch a hole" in files existing on an ext4 filesystem. When punching holes into a file races with the page fault of the same area, it is possible that freed blocks remain referenced from page cache pages mapped to process' address space. 

Thus modification of these blocks can corrupt data someone else is now storing in those blocks when at some point those pages are written to disk.

Upstream fixes:

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ea3d7209ca01da209cda6f0dea8be9cc4b7a933b
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=17048e8a083fec7ad841d88ef0812707fbc7e39f
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=32ebffd3bbb4162da5ff88f9a35dd32d0a28ea70
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=011278485ecc3cd2a3954b5d4c73101d919bf1fa

References:

http://seclists.org/oss-sec/2016/q2/1

Comment 1 Andrej Nemec 2016-04-04 07:29:27 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1323579]

Comment 2 Wade Mealing 2016-04-19 05:11:20 UTC

Statement:

This issue does not affect the Linux kernels as shipped with Red Hat Enterprise Linux 5 and 6.

This issue affects the Linux kernels as shipped with Red Hat Enterprise Linux 7 and MRG-2 kernels.

Comment 4 Fedora Update System 2016-04-19 19:23:08 UTC

kernel-4.4.7-300.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.

Comment 7 Fedora Update System 2016-05-06 19:53:25 UTC

kernel-4.4.8-200.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.

Comment 8 errata-xmlrpc 2017-08-01 19:08:28 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2017:2077 https://access.redhat.com/errata/RHSA-2017:2077

Comment 9 errata-xmlrpc 2017-08-02 07:47:22 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2017:1842 https://access.redhat.com/errata/RHSA-2017:1842

Comment 10 errata-xmlrpc 2017-09-06 20:37:33 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise MRG 2

Via RHSA-2017:2669 https://access.redhat.com/errata/RHSA-2017:2669