Bug 1557555 (CVE-2017-18224)

Summary:	CVE-2017-18224 kernel: race condition due to concurrent access to extent tree in fs/ocfs2/aops.c
Product:	[Other] Security Response	Reporter:	Laura Pardo <lpardo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	airlied, ajax, aquini, bhu, bskeggs, dhoward, ewk, fhrbata, hdegoede, hkrzesin, hwkernel-mgr, ichavero, itamar, jarodwilson, jforbes, jglisse, jkacur, john.j5live, jonathan, josef, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, lwang, mchehab, mguzik, mjg59, nmurray, plougher, rvrbovsk, skozina, steved, vdronov, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 4.16-rc5	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the Linux kernel that fs/ocfs2/aops.c omits use of a semaphore and consequently has a race condition for access to the extent tree during read operations in DIRECT mode. This allows local users to cause a denial of service by modifying a certain e_cpos field.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-03-18 14:51:41 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:	1557557, 1557558
Bug Blocks:	1557559

Description Laura Pardo 2018-03-16 21:26:05 UTC

A flaw was found in the Linux kernel that fs/ocfs2/aops.c omits use of a semaphore and consequently has a race condition for access to the extent tree during read operations in DIRECT mode, which allows local users to cause a denial of service by modifying a certain e_cpos field.

References:

https://marc.info/?t=150884957800012&r=1&w=2

An upstream patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3e4c56d41eef5595035872a2ec5a483f42e8917f

Comment 1 Laura Pardo 2018-03-16 21:27:35 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1557557]

Comment 3 Justin M. Forbes 2018-03-16 22:36:13 UTC

This was fixed for Fedora with the 4.15 rebases.