Bug 2165852 (CVE-2023-0240)

Summary:	CVE-2023-0240 kernel: io_uring: reference counting issue in io_prep_async_work leads to use-after-free
Product:	[Other] Security Response	Reporter:	Mauro Matteo Cascella <mcascell>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	acaringi, bhu, chwhite, crwood, ddepaula, debarbos, dfreiber, dhoward, dvlasenk, ezulian, fhrbata, hkrzesin, jarod, jburrell, jfaracco, jferlan, jforbes, jlelli, joe.lawrence, jshortt, jstancek, jwyatt, kcarcia, kernel-mgr, lgoncalv, lleshchi, lzampier, nmurray, ptalbert, qzhao, rogbas, rvrbovsk, scweaver, tyberry, vkumar, walters, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 5.10	Doc Type:	If docs needed, set a value
Doc Text:	A logic error was found in the io_uring subsystem of the Linux kernel. This issue occurs due to an incorrect assumption that the last io_grab_identity call could not return false in the io_prep_async_work function, leading to reference counting issues and a use-after-free issue. This could allow a local user to crash or escalate their privileges on the system.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-02-02 00:25:56 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:	2165853
Bug Blocks:	2165714

Description Mauro Matteo Cascella 2023-01-31 09:24:05 UTC

There is a logic error in io_uring's implementation which can be used to trigger a use-after-free vulnerability leading to privilege escalation. In the io_prep_async_work function the assumption that the last io_grab_identity call cannot return false is not true, and in this case the function will use the init_cred or the previous linked requests identity to do operations instead of using the current identity. This can lead to reference counting issues causing use-after-free.

Upstream fix:
https://github.com/torvalds/linux/commit/1e6fa5216a0e59ef02e8b6b40d553238a3b81d49

Comment 1 Mauro Matteo Cascella 2023-01-31 09:24:31 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2165853]

Comment 2 Justin M. Forbes 2023-01-31 21:38:19 UTC

This was fixed for Fedora with the 5.10 stable kernel rebases in 2020.

Comment 3 Product Security DevOps Team 2023-02-02 00:25:52 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2023-0240