Bug 1959565 (CVE-2021-3491)

Summary:	CVE-2021-3491 kernel: Linux kernel io_uring PROVIDE_BUFFERS MAX_RW_COUNT bypass
Product:	[Other] Security Response	Reporter:	Pedro Sampaio <psampaio>
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, adscvr, airlied, alciregi, bdettelb, bmasney, brdeoliv, bskeggs, chwhite, crwood, dhoward, dvlasenk, fhrbata, fpacheco, hdegoede, hkrzesin, jarodwilson, jeremy, jforbes, jglisse, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, nmurray, ptalbert, qzhao, rvrbovsk, steved, tomckay, walters, wcosta, 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 flaw was found in the Linux kernel. The io_uring PROVIDE_BUFFERS operation allowed the MAX_RW_COUNT limit to be bypassed, which led to negative values being used in mem_rw when reading /proc/<PID>/mem. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-06-01 14:54:35 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:	1959566, 1966635
Bug Blocks:	1959567

Description Pedro Sampaio 2021-05-11 19:09:25 UTC

It was discovered that io_uring PROVIDE_BUFFERS operation allowed the MAX_RW_COUNT limit to be bypassed, which led to negative values being used
in mem_rw when reading /proc/<PID>/mem.

References:

https://www.openwall.com/lists/oss-security/2021/05/11/13
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d1f82808877bb10d3deee7cf3374a4eb3fb582db

Comment 1 Pedro Sampaio 2021-05-11 19:10:07 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1959566]