Bug 1836936 (CVE-2020-0110)

Summary:	CVE-2020-0110 kernel: out of bound write when writing 0 bytes to PSI files which could result in local privilege escalation
Product:	[Other] Security Response	Reporter:	Michael Kaplan <mkaplan>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	acaringi, airlied, bhu, blc, bmasney, brdeoliv, bskeggs, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, iboverma, ichavero, itamar, jarodwilson, jeremy, jforbes, jglisse, jlelli, john.j5live, jonathan, josef, jross, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, masami256, matt, mchehab, mcressma, mjg59, mlangsdo, nmurray, ptalbert, qzhao, rt-maint, rvrbovsk, steved, 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 Pressure stall information subsystem. This flaw allows a local attacker with the ability to write to root-owned files to corrupt kernel stack memory.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-05-22 21:15:19 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:	1836943
Bug Blocks:	1836944

Description Michael Kaplan 2020-05-18 14:11:28 UTC

In psi_write of psi.c, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.

References: 

https://source.android.com/security/bulletin/2020-05-01

Upstream Commit:

https://git.kernel.org/linus/6fcca0fa48118e6d63733eb4644c6cd880c15b8f

Comment 1 Michael Kaplan 2020-05-18 14:21:15 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1836943]

Comment 2 Justin M. Forbes 2020-05-18 15:10:09 UTC

This was fixed for Fedora with the 5.5.7 stable kernel updates.

Comment 3 Wade Mealing 2020-05-20 02:02:54 UTC

*** Bug 1837790 has been marked as a duplicate of this bug. ***

Comment 8 Wade Mealing 2020-05-20 02:16:43 UTC

Mitigation:

As the attacker must have the ability to write to these files, a possible mitigation would be to reduce the access that users and their processes would have to the files used in the attack.  The files within the /proc/ filesystem can be temporarily modified with the chmod/chown command for each boot.

Comment 10 Product Security DevOps Team 2020-05-22 21:15:19 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-0110