Bug 1243465 (CVE-2015-3290)

Summary:	CVE-2015-3290 kernel: x86: nested NMI handler and espfix64 interaction privilege escalation
Product:	[Other] Security Response	Reporter:	Martin Prpič <mprpic>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	agordeev, aquini, bhu, dhoward, esammons, fhrbata, iboverma, jkacur, jross, kernel-mgr, kstutsma, lgoncalv, lwang, matt, mcressma, mguzik, nmurray, pholasek, plougher, pmatouse, rvrbovsk, security-response-team, vkaigoro, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	A flaw was found in the way the Linux kernel's nested NMI handler and espfix64 functionalities interacted during NMI processing. A local, unprivileged user could use this flaw to crash the system or, potentially, escalate their privileges on the system.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-07-23 07:35:53 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:	1245936
Bug Blocks:	1243467

Description Martin Prpič 2015-07-15 13:42:15 UTC

A flaw was found in the way Linux kernel's nested NMI handler and espfix64 functionalities interacted during NMI processing.

A local, unprivileged user could use this flaw to crash the system or, potentially, escalate their privileges on the system.

Upstream fix:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9b6e6a8334d56354853f9c255d1395c2ba570e0a

Acknowledgements:

Red Hat would like to thank Andy Lutomirski for reporting this issue.

Comment 2 Petr Matousek 2015-07-23 07:23:42 UTC

In order to exploit this issue non-root (non-privileged) user needs to make the Linux kernel's NMI handler perform an iret instruction, which re-enables NMIs and thus the nested NMI code path in the NMI handler is exercised.

To our knowledge, an unprivileged local user can do that since upstream commit https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=e00b12e64be9a34ef071de7b6052ca9ea29dd460.

Comment 3 Petr Matousek 2015-07-23 07:35:53 UTC

Statement:

This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5 and 6 since they did not backport the nested NMI handler and espfix64 functionalities.

This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 7 and Red Hat Enterprise MRG 2 since they did not backport the espfix64 functionality and also did not backport upstream commit e00b12e64be9a3 that allowed an unprivileged local user to re-enable NMIs from the NMI handler.

Comment 4 Petr Matousek 2015-07-23 07:37:57 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1245936]