Bug 1791959 (CVE-2019-20096)

Summary:	CVE-2019-20096 kernel: memory leak in __feat_register_sp() in net/dccp/feat.c
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	acaringi, airlied, 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, mlangsdo, nmurray, qzhao, rtillery, rt-maint, rvrbovsk, steved, williams, wmealing
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’s implementation of the Datagram Congestion Control Protocol (DCCP). A local attacker with access to the system can create DCCP sockets to cause a memory leak and repeat this operation to exhaust all memory and panic the system.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-12-15 11:13:03 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:	1791960, 1795867, 1795868, 1795869, 1795870, 1795871, 1795872
Bug Blocks:	1791962

Description Guilherme de Almeida Suckevicz 2020-01-16 19:06:44 UTC

A flaw was found in the linux kernels implementation of DCCP protocol in which a local user can create a memory leak by setting options on a dccp socket. An attacker must have a local account access on the system, this is not a remote attack.

Reference:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1d3ff0950e2b40dc861b1739029649d03f591820

Comment 1 Guilherme de Almeida Suckevicz 2020-01-16 19:07:36 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1791960]

Comment 2 Justin M. Forbes 2020-01-16 20:57:08 UTC

That was fixed for Fedora with the 5.1 kernel rebases.

Comment 5 Wade Mealing 2020-01-29 04:21:58 UTC

Mitigation:

As the DCCP module will be auto-loaded when required, its use can be disabled.  Red Hat Enterprise Linux 7.5 (and later) and 8.0 (and later) already have this disabled, but for any other version, the system can prevent the module from loading with the following instructions :

  # echo "install dccp /bin/true" >> /etc/modprobe.d/disable-dccp.conf 
 
The system will need to be restarted if the DCCP modules are loaded. In most circumstances, the DCCP kernel modules will be unable to be unloaded while any network interfaces are active and the protocol is in use.

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