Bug 1947994 (CVE-2020-36311)

Summary:	CVE-2020-36311 kernel: DoS by triggering destruction of a large SEV VM
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bhu, blc, bmasney, chwhite, crwood, dvlasenk, hdegoede, hkrzesin, jarodwilson, jeremy, jforbes, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mlangsdo, nmurray, ptalbert, qzhao, rvrbovsk, steved, walters, 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. This flaw allows attackers to cause a denial of service (soft lockup) by triggering the destruction of a large SEV VM, which requires unregistering many encrypted regions. The highest threat from this vulnerability is to system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:		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:	1961037, 1947996, 1960868, 1960869
Bug Blocks:	1947995

Description Guilherme de Almeida Suckevicz 2021-04-09 17:20:02 UTC

An issue was discovered in the Linux kernel before 5.9. arch/x86/kvm/svm/sev.c allows attackers to cause a denial of service (soft lockup) by triggering destruction of a large SEV VM (which requires unregistering many encrypted regions).

Reference and upstream patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7be74942f184fdfba34ddd19a0d995deb34d4a03

Comment 1 Guilherme de Almeida Suckevicz 2021-04-09 17:21:38 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1947996]

Comment 2 Justin M. Forbes 2021-04-12 21:25:23 UTC

This was fixed for Fedora with the 5.9 kernel rebases.

Comment 3 Mauro Matteo Cascella 2021-05-14 15:05:58 UTC

For a general description of what a CPU soft lockup is, refer to https://access.redhat.com/articles/371803.