Bug 2237901

Summary:	kernel: net/sched: A use-after-free vulnerability in the Linux kernel's cls_fw component that can be exploited to achieve local privilege escalation.
Product:	[Other] Security Response	Reporter:	juneau
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	CLOSED DUPLICATE	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, allarkin, bhu, chwhite, dbohanno, debarbos, dfreiber, dvlasenk, ezulian, hkrzesin, jarod, jburrell, jdenham, jfaracco, jforbes, jlelli, joe.lawrence, jshortt, jstancek, jwyatt, kcarcia, ldoskova, lgoncalv, lleshchi, lzampier, nmurray, ptalbert, rogbas, rrobaina, rvrbovsk, rysulliv, scweaver, tglozar, tyberry, vkumar, walters, wcosta, williams, wmealing, ycote
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 use-after-free vulnerability was found in the Linux kernel's net/sched: cls_fw component that can be exploited to achieve local privilege escalation.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-10-25 12:19:56 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:	2238209
Bug Blocks:	2237759

Description juneau 2023-09-07 15:40:07 UTC

A use-after-free vulnerability in the Linux kernel's net/sched: cls_fw component can be exploited to achieve local privilege escalation.

When fw_change() is called on an existing filter, the whole tcf_result struct is always copied into the new instance of the filter. This causes a problem when updating a filter bound to a class, as tcf_unbind_filter() is always called on the old instance in the success path, decreasing filter_cnt of the still referenced class and allowing it to be deleted, leading to a use-after-free.

We recommend upgrading past commit 76e42ae831991c828cffa8c37736ebfb831ad5ec.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76e42ae831991c828cffa8c37736ebfb831ad5ec
https://kernel.dance/76e42ae831991c828cffa8c37736ebfb831ad5ec

Comment 1 Alex 2023-09-10 08:26:24 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2238209]

Comment 3 Justin M. Forbes 2023-09-13 11:51:57 UTC

This was fixed for Fedora with the 6.4.10 stable kernel updates.

Comment 9 Alex 2023-10-25 12:19:56 UTC


*** This bug has been marked as a duplicate of bug 2225511 ***