Bug 1798708 (CVE-2019-20422)

Summary:	CVE-2019-20422 kernel: mishandling the RT6_LOOKUP_F_DST_NOREF flag in fib6_rule_lookup in net/ipv6/ip6_fib.c
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, airlied, bhu, blc, brdeoliv, bskeggs, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, iboverma, ichavero, itamar, jarodwilson, jeremy, jforbes, jglisse, jlelli, john.j5live, jonathan, josef, jross, jshortt, jstancek, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, masami256, matt, mchehab, mcressma, mjg59, mlangsdo, nmurray, 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 flaw was found in the Linux kernel prior to version 5.3.4. Affected code was introduced in a recent patch of fib6_rule_lookup in net/ipv6/ip6_fib.c in the IPv6 subsystem of the kernel which was found to mishandle the RT6_LOOKUP_F_DST_NOREF flag in a reference-count decision, leading to a crash. Availability is the highest threat from this vulnerability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-02-18 20:09:41 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:	1798709
Bug Blocks:	1798710

Description Guilherme de Almeida Suckevicz 2020-02-05 20:04:19 UTC

In the Linux kernel before 5.3.4, fib6_rule_lookup in net/ipv6/ip6_fib.c mishandles the RT6_LOOKUP_F_DST_NOREF flag in a reference-count decision, leading to (for example) a crash that was identified by syzkaller.

Reference and upstream commit:
https://github.com/torvalds/linux/commit/7b09c2d052db4b4ad0b27b97918b46a7746966fa

Comment 1 Guilherme de Almeida Suckevicz 2020-02-05 20:06:10 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1798709]

Comment 2 Rohit Keshri 2020-02-06 09:33:01 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 4 Product Security DevOps Team 2020-02-18 20:09:41 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-2019-20422

Comment 7 Eric Christensen 2020-02-21 19:34:55 UTC

Statement:

The affected code was not introduced into any kernel versions shipped with Red Hat Enterprise Linux making this vulnerable not applicable to these platforms.