Bug 1923738 (CVE-2021-20219)

Summary:	CVE-2021-20219 kernel: improper synchronization in flush_to_ldisc() can lead to DoS
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bhu, blc, bmasney, chwhite, crwood, dramseur, dvlasenk, hdegoede, hkrzesin, jarodwilson, jeremy, jforbes, jhunter, jlelli, jonathan, josef, jross, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mlangsdo, nmurray, ptalbert, qzhao, rkeshri, rt-maint, rvrbovsk, steved, walters, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 4.18	Doc Type:	If docs needed, set a value
Doc Text:	A denial of service vulnerability was found in n_tty_receive_char_special in drivers/tty/n_tty.c of the Linux kernel. In this flaw a local attacker with a normal user privilege could delay the loop (due to a changing ldata->read_head, and a missing sanity check) and cause a threat to the system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:		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:	1909882, 1924152, 1924153
Bug Blocks:	1910136

Description Guilherme de Almeida Suckevicz 2021-02-01 18:25:05 UTC

A denial-of-service vulnerability was found in n_tty_receive_char_special in drivers/tty/n_tty.c of the Linux kernel.  In this flaw a local attacker with a normal user privilege could  delay the loop (due to a changing ldata->read_head, and a missing sanity check) and cause a threat to the system availability.

Comment 4 Rohit Keshri 2021-02-02 08:02:10 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 6 Rohit Keshri 2021-02-02 17:12:01 UTC

Acknowledgments:

Name: Evgenii Shatokhin (Virtuozzo Research LLC)