Bug 1771486 (CVE-2019-18198)

Summary:	CVE-2019-18198 kernel: reference count usage error in fib6_rule_suppress function in net/ipv6/fib6_rules.c
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
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, bdettelb, bhu, blc, brdeoliv, bskeggs, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, iboverma, ichavero, itamar, jarodwilson, jeremy, jforbes, jlelli, john.j5live, jonathan, josef, jross, jshortt, jstancek, jwboyer, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mcressma, mjg59, mkaplan, mlangsdo, nmurray, qzhao, rt-maint, rvrbovsk, steved, williams, wmealing
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	Kernel 5.4	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the Linux kernel’s IPv6 routing system. A local attacker with the ability to configure routing can create a situation where they can corrupt memory or possibly escalate privileges.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-10-25 09:56:07 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:	1771487, 1814527
Bug Blocks:	1771490, 2008467

Description Guilherme de Almeida Suckevicz 2019-11-12 13:19:45 UTC

A flaw was found in the Linux kernels IPV6 subsystem.  Route reference count usage error in the fib6_rule_suppress() function in the fib6 suppression feature of net/ipv6/fib6_rules.c.  A local attacker with the ability to trigger packets being sent over a specific route that implements suppress_prefixlength.  

The suppress_prefixlength routes are not standard and require administrative access to insert.


Upstream commit:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ca7a03c4175366a92cee0ccc4fec0038c3266e26

Comment 1 Guilherme de Almeida Suckevicz 2019-11-12 13:20:08 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1771487]

Comment 2 Justin M. Forbes 2019-11-12 18:06:44 UTC

This was fixed for Fedora with the 5.3.4 stable kernel updates.

Comment 7 Wade Mealing 2020-03-18 06:30:35 UTC

Mitigation:


As the IPV6 module will be auto-loaded when required, its use can be disabled  by preventing the module from loading with the following instructions:

https://access.redhat.com/solutions/8790

If the system requires IPV6 to work correctly, this mitigation may not be suitable.

If you need further assistance, see KCS article https://access.redhat.com/solutions/41278 or contact Red Hat Global Support Services.

Comment 10 Petr Matousek 2020-04-03 04:31:26 UTC

Statement:

This flaw is rated as moderate as setting up the condition requires CAP_NET_ADMIN privileges which are not available to regular users.

Comment 20 Rohit Keshri 2021-12-06 07:52:40 UTC

*** Bug 2014623 has been marked as a duplicate of this bug. ***