Bug 1856441 (CVE-2020-15852)

Summary:	CVE-2020-15852 xen: Linux ioperm bitmap context switching issues
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
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, mcascell, mchehab, mcressma, mjg59, mlangsdo, nmurray, ptalbert, qzhao, rt-maint, rvrbovsk, security-response-team, steved, williams
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, in the way IOPL and IOPERM system calls were handled during context switches in x86 PV guests. This flaw allows a local guest user to escalate their privileges to the guest. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-07-16 19:27:36 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:	1857794
Bug Blocks:	1856442

Description Guilherme de Almeida Suckevicz 2020-07-13 16:26:09 UTC

Linux 5.5 overhauled the internal state handling for the iopl() and ioperm() system calls.  Unfortunately, one aspect on context switch wasn't wired up correctly for the Xen PVOps case.

Comment 1 Mauro Matteo Cascella 2020-07-16 13:59:06 UTC

Acknowledgments:

Name: the Xen project

Comment 2 Mauro Matteo Cascella 2020-07-16 14:05:50 UTC

External References:

https://xenbits.xen.org/xsa/advisory-329.html

Comment 3 Mauro Matteo Cascella 2020-07-16 14:53:39 UTC

Statement:

The vulnerability can only be exploited in domains which have been granted access to IO ports by Xen. This is typically only the hardware domain, and PV guests configured with PCI passthrough. x86 HVM/PVH guests are not affected by this flaw.

Comment 4 Mauro Matteo Cascella 2020-07-16 15:11:30 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1857794]

Comment 9 Justin M. Forbes 2020-10-08 19:12:55 UTC

This was fixed for Fedora with the 5.7.10 stable kernel updates.