Bug 1934727 (CVE-2021-20286)

Summary:	CVE-2021-20286 libnbd: Assertion failure in nbd_unlocked_opt_go in lib/opt.c
Product:	[Other] Security Response	Reporter:	Pedro Sampaio <psampaio>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	eblake, mcascell, rjones, tzheng, virt-maint
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	libnbd 1.7.3	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in libnbd. A malicious server may be able to kill a client application using libnbd due to an assertion failure in nbd_unlocked_opt_go() leading to denial of service. 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:	1937890, 1937891, 1938143
Bug Blocks:	1934728, 1937913

Description Pedro Sampaio 2021-03-03 18:14:22 UTC

A flaw was found in libnbd. An assertion failure in in nbd_unlocked_opt_go in ilb/opt.c may lead to denial of service.

Comment 2 Mauro Matteo Cascella 2021-03-11 16:39:31 UTC

Upstream fix:
https://gitlab.com/nbdkit/libnbd/-/commit/fb4440de9cc76e9c14bd3ddf3333e78621f40ad0

Comment 4 Richard W.M. Jones 2021-03-11 17:07:43 UTC

It's really all Eric's work, I just tested his patch.

Comment 5 Mauro Matteo Cascella 2021-03-11 17:10:04 UTC

Acknowledgments:

Name: Eric Blake (Red Hat)

Comment 11 Mauro Matteo Cascella 2021-03-22 10:19:08 UTC

Statement:

Red Hat Enterprise Linux 8 is not affected by this issue. The affected API was introduced in upstream `libnbd` version 1.4 which is only shipped in RHEL Advanced Virtualization 8.3.0 onward.