Bug 1914719 (CVE-2021-20177)

Summary:	CVE-2021-20177 kernel: iptables string match rule could result in kernel panic
Product:	[Other] Security Response	Reporter:	Wade Mealing <wmealing>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bhu, blc, bmasney, brdeoliv, bskeggs, chwhite, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, iboverma, itamar, jarodwilson, jeremy, jforbes, jglisse, jlelli, jonathan, josef, jross, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mcressma, mlangsdo, nmurray, pmatouse, ptalbert, qzhao, rt-maint, rvrbovsk, steved, walters, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 5.5-rc1	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the Linux kernel's implementation of string matching within a packet. A privileged user (with root or CAP_NET_ADMIN) when inserting iptables rules could insert a rule which can panic the system.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-01-11 06:27:42 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:	1914720
Bug Blocks:	1913711

Description Wade Mealing 2021-01-11 01:53:33 UTC

A flaw was found in the Linux kernels implementation of string matching within a packet.  A privileged user ( with root or CAP_NET_ADMIN ) when inserting iptables rules could insert a rule which can panic the system.

This could lead to a denial of service or possibly worse. Further investigation is ongoing.

Upstream patch:
https://github.com/torvalds/linux/commit/ca58fbe06c54

Upstream bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=209823

Comment 1 Wade Mealing 2021-01-11 01:54:00 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1914720]

Comment 5 Wade Mealing 2021-01-11 02:39:10 UTC

Mitigation:

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

Comment 8 Justin M. Forbes 2021-01-22 13:15:19 UTC

This was fixed for Fedora with the 5.5 kernel rebases.