Bug 1903262 (CVE-2020-29369)

Summary:	CVE-2020-29369 kernel: race condition between expand_downwards and expand_upwards and page-table free operations from an munmap call
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
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, aquini, asavkov, bhu, blc, bmasney, brdeoliv, bskeggs, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, iboverma, itamar, jarodwilson, jeremy, jforbes, jglisse, jlelli, joe.lawrence, jonathan, josef, jpoimboe, jross, jshortt, jstancek, jthierry, jwboyer, kcarcia, kernel-maint, kernel-mgr, kpatch-maint, lgoncalv, linville, masami256, mchehab, mcressma, mjg59, mlangsdo, nmurray, ptalbert, qzhao, rhandlin, rt-maint, rvrbovsk, steved, walters, 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 flaw was found in the Linux kernel. A race condition between certain expand functions and page-table free operations from an munmap call leading to ... FIXME. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-12-07 15:36:09 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:	1903263, 1903473, 1903474, 1903475, 1903476, 1903477, 1903478, 1903479, 1903480, 1903481, 1903482, 1903484, 1903485, 1903486, 1903487, 1903488, 1903489, 1903490, 1903491, 1903492, 1903493, 1903494, 1903495
Bug Blocks:	1903264

Description Guilherme de Almeida Suckevicz 2020-12-01 17:39:43 UTC

An issue was discovered in mm/mmap.c in the Linux kernel before 5.7.11. There is a race condition between certain expand functions (expand_downwards and expand_upwards) and page-table free operations from an munmap call.

Reference:
https://bugs.chromium.org/p/project-zero/issues/detail?id=2056

Upstream patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=246c320a8cfe0b11d81a4af38fa9985ef0cc9a4c

Comment 1 Guilherme de Almeida Suckevicz 2020-12-01 17:40:32 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1903263]

Comment 6 Wade Mealing 2020-12-02 08:15:40 UTC

Mitigation:


There is no mitigation available at this time.  Red Hat is investigating a kpatch as an option to fix this issue on kpatch supported streams.

Comment 8 Justin M. Forbes 2020-12-02 14:20:28 UTC

This was fixed for Fedora with the 5.7.11 stable kernel updates.

Comment 15 Wade Mealing 2020-12-03 03:35:12 UTC

Removing needinfo as I think most of them are no longer relevant.