Bug 1860065 (CVE-2020-0305)

Summary:	CVE-2020-0305 kernel: possible use-after-free due to a race condition in cdev_get of char_dev.c
Product:	[Other] Security Response	Reporter:	Marian Rehak <mrehak>
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, 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, lgoncalv, linville, masami256, matt, mchehab, mcressma, mjg59, mlangsdo, nmurray, ptalbert, qzhao, rt-maint, rvrbovsk, 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 use-after-free flaw was found in the way the Linux kernel's filesystem subsystem handled a race condition in the chrdev_open function. This flaw allows a privileged local user to starve the resources, causing a denial of service or potentially escalating their privileges. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-11-04 02:26:24 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:	1890062, 1890063, 1890064, 1890065, 1890066, 1860066, 1866323, 1866324, 1866325, 1866326, 1866327
Bug Blocks:	1860068

Description Marian Rehak 2020-07-23 16:19:46 UTC

In cdev_get of char_dev.c, there is a possible use-after-free due to a race condition. This could lead to local escalation of privilege with System execution privileges needed.

Reference:

https://android.googlesource.com/kernel/common/+/68faa679b8be1a74e6663c21c3a9d25d3

Comment 1 Marian Rehak 2020-07-23 16:20:18 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1860066]

Comment 2 Justin M. Forbes 2020-07-23 19:06:58 UTC

This was fixed for Fedora with the 5.4.12 stable kernel updates.

Comment 6 Alex 2020-08-05 11:14:38 UTC

Mitigation:

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Comment 9 Petr Matousek 2020-08-06 11:23:31 UTC

Statement:

This issue is rated as having Moderate impact because of the preconditions needed to trigger the issue (elevated/root privileges).

Comment 10 Petr Matousek 2020-08-06 11:23:39 UTC

External References:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=68faa679b8be1a74e6663c21c3a9d25d32f1c079

Comment 12 errata-xmlrpc 2020-11-04 00:51:18 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2020:4431 https://access.redhat.com/errata/RHSA-2020:4431

Comment 13 errata-xmlrpc 2020-11-04 02:23:47 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2020:4609 https://access.redhat.com/errata/RHSA-2020:4609

Comment 14 Product Security DevOps Team 2020-11-04 02:26:24 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-2020-0305