Bug 1549586 (CVE-2017-18200)

Summary:	CVE-2017-18200 kernel: mishandling reference counts associated with f2fs_wait_discard_bios calls allowing local attacker to cause denial of service
Product:	[Other] Security Response	Reporter:	Adam Mariš <amaris>
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, blc, bskeggs, dhoward, esammons, ewk, fhrbata, hdegoede, hkrzesin, hwkernel-mgr, iboverma, ichavero, itamar, jarodwilson, jforbes, jglisse, jkacur, john.j5live, jonathan, josef, jross, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, lwang, matt, mchehab, mcressma, mguzik, mjg59, mlangsdo, nmurray, plougher, rt-maint, rvrbovsk, skozina, steved, vdronov, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 4.14	Doc Type:	If docs needed, set a value
Doc Text:	The f2fs implementation in the Linux kernel, before 4.14, mishandles reference counts associated with f2fs_wait_discard_bios calls. This allows local users to cause a denial of service (BUG), as demonstrated by fstrim.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-03-01 14:22:45 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:	1550580
Bug Blocks:	1549588

Description Adam Mariš 2018-02-27 13:19:12 UTC

The f2fs implementation in the Linux kernel before 4.14 mishandles reference counts associated with f2fs_wait_discard_bios calls, which allows local users to cause a denial of service (BUG), as demonstrated by fstrim.

An upstream patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=638164a2718f337ea224b747cf5977ef143166a4

Comment 2 Vladislav Dronov 2018-03-01 14:16:45 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1550580]

Comment 4 Vladislav Dronov 2018-03-01 14:22:45 UTC

Statement:

This issue does not affect the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 5, 6, 7, its real-time kernel, Red Hat Enterprise MRG 2, Red Hat Enterprise Linux 7 for ARM 64 and Red Hat Enterprise Linux 7 for Power 9 LE, as the code with the flaw is not built and shipped in the products listed.

Comment 5 Justin M. Forbes 2018-03-01 16:06:30 UTC

This was fixed in 4.14 rebases for all Fedora releases.