Bug 2282353 (CVE-2021-47387)

Summary:	CVE-2021-47387 kernel: cpufreq: schedutil: Use kobject release() method to free sugov_tunables
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, pauld, ptalbert, rkeshri, rparrazo, rrobaina, rvrbovsk, scweaver, sidakwo, sukulkar, tglozar, vkumar, wcosta, williams, wmealing, ycote, ykopkova, zhijwang
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 4.9.285, kernel 4.14.249, kernel 4.19.209, kernel 5.4.151, kernel 5.10.71, kernel 5.14.10, kernel 5.15	Doc Type:	If docs needed, set a value
Doc Text:		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:	2282406

Description ybuenos 2024-05-22 09:05:47 UTC

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

cpufreq: schedutil: Use kobject release() method to free sugov_tunables

The Linux kernel CVE team has assigned CVE-2021-47387 to this issue.

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024052145-CVE-2021-47387-7c1e@gregkh/T

Comment 5 Alex 2024-06-09 17:41:40 UTC

The result of automatic check (that is developed by Alexander Larkin) for this CVE-2021-47387 is: CHECK	Maybe valid. Check manually. with impact LOW (that is an approximation based on flags INIT WARNONLY  ; 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.

Comment 7 ybuenos 2024-06-18 16:07:33 UTC

Alex, any thoughts regarding the above?

Comment 8 Alex 2024-06-19 11:51:49 UTC

In reply to comment #7:
> Alex, any thoughts regarding the above?

I agree to keep it Low.
Looks like bug can happen only during initialization/exit of this kernel module.

Also I read about "sugov" a little bit and it looks like this is specific module for RT:
"In system where multiple CPUs shares the same frequency domain a small
workload on a CPU can still be subject to frequency spikes, generated by
the activation of the sugov's kthread.

Since the sugov kthread is a special RT task, which goal is just that to
activate a frequency transition, ..".

And I cannot think of scenario how regular local user can use it (trigger this bug), so PR:H for CVSS.