Bug 2164424 (CVE-2022-4696)

Summary:	CVE-2022-4696 kernel: user-after-free during IORING_OP_SPLICE operation
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:	medium	Docs Contact:
Priority:	medium
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:		Doc Type:	If docs needed, set a value
Doc Text:	A use-after-free flaw was found in the io_uring subsystem of the Linux kernel. This issue occurs during the IORING_OP_SPLICE operation due to a missing IO_WQ_WORK_FILES flag, leading to an invalid decrease of its reference counter and later causing the use-after-free vulnerability. This flaw allows a local user to crash or potentially escalate their privileges on the system.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-01-27 23:52:13 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:	2164425
Bug Blocks:	2160255

Description Mauro Matteo Cascella 2023-01-25 14:13:04 UTC

A use-after-free vulnerability was found in the Linux kernel through io_uring and the IORING_OP_SPLICE operation. IORING_OP_SPLICE is missing the IO_WQ_WORK_FILES flag, which signals that the operation won't use current->nsproxy, so its reference counter is not increased. This assumption is not always true as calling io_splice on specific files will call the get_uts function which will use current->nsproxy leading to invalidly decreasing its reference counter later causing the use-after-free vulnerability.

Upstream commit:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=75454b4bbfc7e6a4dd8338556f36ea9107ddf61a

Comment 1 Mauro Matteo Cascella 2023-01-25 14:13:33 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2164425]

Comment 3 Justin M. Forbes 2023-01-25 14:40:09 UTC

This was fixed for Fedora with the 5.12 rebases.

Comment 4 Product Security DevOps Team 2023-01-27 23:52:09 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-2022-4696