Bug 1921958 (CVE-2021-3348)

Summary:	CVE-2021-3348 kernel: Use-after-free in ndb_queue_rq() in drivers/block/nbd.c
Product:	[Other] Security Response	Reporter:	Pedro Sampaio <psampaio>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bhu, blc, bmasney, brdeoliv, bskeggs, chwhite, dhoward, dramseur, dvlasenk, fhrbata, hdegoede, hkrzesin, itamar, jarodwilson, jeremy, jforbes, jhunter, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, kmitts, kpatch-maint, lgoncalv, linville, masami256, mchehab, mgala, mlangsdo, nmurray, ptalbert, qzhao, rhandlin, rvrbovsk, security-response-team, 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 use after free flaw in the Linux kernel network block device (NBD) subsystem was found in the way user calls an ioctl NBD_SET_SOCK at a certain point during device setup.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-11-09 15:31:22 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:	1921960, 1927246, 1927247, 1927255
Bug Blocks:	1921962

Description Pedro Sampaio 2021-01-28 23:52:15 UTC

A flaw was found in the Linux kernel. A race codition in nbd ioctl may lead to a use-after-free read in nbd_queue_rq causing a crash.

Upstream patch:

https://lore.kernel.org/linux-block/24dff677353e2e30a71d8b66c4dffdbdf77c4dbd.1611595239.git.josef@toxicpanda.com/

References:

https://www.openwall.com/lists/oss-security/2021/01/28/3

Comment 1 Pedro Sampaio 2021-01-28 23:54:27 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1921960]

Comment 3 Alex 2021-02-10 11:57:15 UTC

External References:

https://lore.kernel.org/linux-block/24dff677353e2e30a71d8b66c4dffdbdf77c4dbd.1611595239.git.josef@toxicpanda.com/

Comment 4 Alex 2021-02-10 11:57:23 UTC

Mitigation:

To mitigate this issue, prevent the module nbd from being loaded. Please see https://access.redhat.com/solutions/41278 for information on how to blacklist a kernel module to prevent it from loading automatically.

Comment 8 Petr Matousek 2021-02-11 12:49:41 UTC

Statement:

This flaw is rated as having a Moderate impact because in the default configuration, the issue can only be triggered by a privileged local user (with access to the nbd device).

Comment 9 Justin M. Forbes 2021-03-04 21:59:38 UTC

This was fixed for Fedora with the 5.10.13 stable kernel updates.

Comment 25 errata-xmlrpc 2021-11-09 17:21:36 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4140 https://access.redhat.com/errata/RHSA-2021:4140

Comment 26 errata-xmlrpc 2021-11-09 18:23:35 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4356 https://access.redhat.com/errata/RHSA-2021:4356