Bug 1903249 (CVE-2020-29374)

Summary:	CVE-2020-29374 kernel: the get_user_pages implementation when used for a copy-on-write page does not properly consider the semantics of read operations and therefore can grant unintended read access
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	aarcange, acaringi, adscvr, airlied, aquini, bhu, bmasney, brdeoliv, bskeggs, ddutile, dhoward, dvlasenk, fhrbata, hdegoede, hkrzesin, itamar, jarod, jarodwilson, jeremy, jforbes, jlelli, jonathan, josef, jpazdziora, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mjg59, nmurray, ptalbert, qzhao, rvrbovsk, sgrubb, steved, 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:	An issue was discovered in the Linux kernel related to mm/gup.c and mm/huge_memory.c. The get_user_pages (aka gup) implementation, when used for a copy-on-write page, does not properly consider the semantics of read operations and therefore can grant unintended read access.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-12-15 11:21:01 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:	1903251, 1974670, 1974671, 1974672, 1974673, 1975127, 1975128, 1975129, 1975130
Bug Blocks:	1903252

Description Guilherme de Almeida Suckevicz 2020-12-01 17:15:38 UTC

An issue was discovered in the Linux kernel before 5.7.3, related to mm/gup.c and mm/huge_memory.c. The get_user_pages (aka gup) implementation, when used for a copy-on-write page, does not properly consider the semantics of read operations and therefore can grant unintended write access.

Reference:
https://bugs.chromium.org/p/project-zero/issues/detail?id=2045

Upstream commit:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=17839856fd588f4ab6b789f482ed3ffd7c403e1f

Comment 1 Guilherme de Almeida Suckevicz 2020-12-01 17:16:34 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1903251]

Comment 2 Justin M. Forbes 2020-12-02 14:17:58 UTC

This was fixed for Fedora with the 5.6.19 stable kernel updates.