Bug 1915823 (CVE-2020-35517)

Summary:	CVE-2020-35517 QEMU: virtiofsd: potential privileged host device access from guest
Product:	[Other] Security Response	Reporter:	Prasad Pandit <ppandit>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:	menli <menli>
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	ailan, berrange, cfergeau, dgilbert, drjones, imammedo, itamar, jen, jferlan, jinzhao, jmaloy, juzhang, knoel, mkenneth, mrezanin, mst, ondrejj, pbonzini, philmd, ribarry, rjones, security-response-team, stefanha, virt-maint, virt-maint, vkuznets, xen-maint
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 qemu. A host privilege escalation issue was found in the virtio-fs shared file system daemon where a privileged guest user is able to create a device special file in the shared directory and use it to r/w access host devices. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-03-03 19:01:52 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:	1919106, 1919109, 1919110, 1919111, 1919112, 1919113, 1920740, 1922046, 1929015
Bug Blocks:	1906357

Description Prasad Pandit 2021-01-13 13:43:05 UTC

A potential host privilege escalation issue was found in the virtio-fs shared file system daemon (virtiofsd) of the QEMU. Virtio-fs daemon shares host directory tree with a guest VM. The said privilege escalation scenario may occur if a privileged guest user was to create device special file in the shared directory and use it to r/w access host devices. A privileged guest user may use this flaw to arbitrarily access (r/w) host files resulting in DoS scenario or may potentially reach privilege escalation on the host.

Upstream patch:
---------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg05461.html

Comment 1 Prasad Pandit 2021-01-13 13:43:10 UTC

External References:

https://virtio-fs.gitlab.io/
https://www.openwall.com/lists/oss-security/2021/01/22/1

Comment 3 Prasad Pandit 2021-01-19 14:44:29 UTC

Acknowledgments:

Name: Alex Xu (alxu.ca)

Comment 4 Prasad Pandit 2021-01-22 07:51:22 UTC

Created qemu tracking bugs for this issue:

Affects: fedora-all [bug 1919106]

Comment 6 Prasad Pandit 2021-01-22 08:45:07 UTC

Statement:

This issue does not affect the version of the qemu-kvm package as shipped with the Red Hat Enterprise Linux 5, 6 and 7. Virtio-fs is fairly new and is not built in the Red Hat Enterprise Linux 5, 6 and 7.

This issue affects the version of the qemu-kvm package as shipped with the Red Hat Enterprise Linux 8. Future qemu-kvm package updates for Red Hat Enterprise Linux 8 may address this issue.

Comment 10 errata-xmlrpc 2021-03-03 13:03:10 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:0711 https://access.redhat.com/errata/RHSA-2021:0711

Comment 11 Product Security DevOps Team 2021-03-03 19:01:52 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-2020-35517

Comment 12 errata-xmlrpc 2021-03-08 10:13:18 UTC

This issue has been addressed in the following products:

  Advanced Virtualization for RHEL 8.2.1

Via RHSA-2021:0743 https://access.redhat.com/errata/RHSA-2021:0743