Bug 2283394 (CVE-2021-47555)

Summary:	CVE-2021-47555 kernel: net: vlan: fix underflow for the real_dev refcnt
Product:	[Other] Security Response	Reporter:	ybuenos
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	acaringi, allarkin, aquini, bhu, chwhite, cye, cyin, dbohanno, debarbos, dfreiber, drow, dvlasenk, esandeen, ezulian, hkrzesin, jarod, jburrell, jdenham, jfaracco, jlelli, joe.lawrence, jshortt, jstancek, jwyatt, kcarcia, ldoskova, lgoncalv, lzampier, mleitner, mmilgram, mstowell, nmurray, ptalbert, rkeshri, rparrazo, rrobaina, rvrbovsk, rysulliv, scweaver, sidakwo, sukulkar, tglozar, tyberry, vkumar, wcosta, williams, wmealing, ycote, ykopkova, zhijwang
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 5.4.163, kernel 5.10.83, kernel 5.15.6	Doc Type:	If docs needed, set a value
Doc Text:	A vulnerability was found in the Linux kernel's VLAN implementation in the handling of reference counts for the underlying device, where the issue occurs when the reference count for the real_dev is decremented without a corresponding increment, leading to an underflow condition when a VLAN device is removed, resulting in memory leaks and DoS during device unregistration.	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:
Bug Blocks:	2283496

Description ybuenos 2024-05-27 09:41:43 UTC

In the Linux kernel, the following vulnerability has been resolved:

net: vlan: fix underflow for the real_dev refcnt

The Linux kernel CVE team has assigned CVE-2021-47555 to this issue.

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024052443-CVE-2021-47555-3043@gregkh/T

Comment 4 Alex 2024-06-09 17:52:03 UTC

The result of automatic check (that is developed by Alexander Larkin) for this CVE-2021-47555 is: CHECK	Maybe valid. Check manually. with impact LOW (that is an approximation based on flags INIT WARNONLY LEAK UAF  ; these flags parsed automatically based on patch data). Such automatic check happens only for Low/Moderates (and only when not from reporter, but parsing already existing CVE). Highs always checked manually (I check it myself and then we check it again in Remediation team). In rare cases some of the Moderates could be increased to High later.