Bug 2225097 (CVE-2023-3776)

Summary:	CVE-2023-3776 kernel: net/sched: cls_fw component can be exploited as result of failure in tcf_change_indev function
Product:	[Other] Security Response	Reporter:	Alex <allarkin>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	acaringi, allarkin, bhu, chwhite, dbohanno, ddepaula, debarbos, dfreiber, dvlasenk, ezulian, hkrzesin, jarod, jburrell, jdenham, jfaracco, jferlan, jforbes, jlelli, joe.lawrence, jpoimboe, jshortt, jstancek, jwyatt, kcarcia, kernel-mgr, kpatch-maint, ldoskova, lgoncalv, lleshchi, lzampier, nmurray, ptalbert, qzhao, rhandlin, rkeshri, rogbas, rrobaina, rvrbovsk, rysulliv, scweaver, swood, tglozar, tyberry, vkumar, walters, wcosta, williams, wmealing, ycote, ymankad
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	Kernel 6.5-rc2	Doc Type:	If docs needed, set a value
Doc Text:	A use-after-free vulnerability was found in fw_set_parms in net/sched/cls_fw.c in network scheduler sub-component in the Linux Kernel. This issue occurs due to a missing sanity check during cleanup at the time of failure, leading to a misleading reference. This may allow a local attacker to gain local privilege escalation.	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:	2225102, 2225103, 2225636, 2225637, 2225638, 2225639, 2225640, 2225641, 2225642, 2225643, 2225644, 2225645, 2225646, 2225647, 2225648, 2225649, 2225650, 2225651, 2225652, 2225653, 2225654, 2225655, 2225657, 2225658, 2225659, 2225660, 2225661, 2225662, 2225663, 2225664, 2225665, 2226640, 2225656
Bug Blocks:	2225092

Description Alex 2023-07-24 10:19:36 UTC

A flaw in the Linux Kernel found. A use-after-free vulnerability in the Linux kernel's net/sched: cls_fw component can be exploited to achieve local privilege escalation. If tcf_change_indev() fails, fw_set_parms() will immediately return an error after incrementing or decrementing the reference counter in tcf_bind_filter(). If an attacker can control the reference counter and set it to zero, they can cause the reference to be freed, leading to a use-after-free vulnerability.

Reference:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=0323bce598eea038714f941ce2b22541c46d488f