Bug 1324867 (CVE-2016-2085)

Summary:	CVE-2016-2085 kernel: timing side channel vulnerability in the Linux Extended Verification Module
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	agordeev, aquini, arm-mgr, bhu, blc, carnil, dhoward, esammons, fhrbata, gansalmon, iboverma, itamar, jforbes, jkacur, joelsmith, jonathan, jross, jwboyer, kernel-maint, kernel-mgr, kstutsma, lgoncalv, lwang, madhu.chinakonda, matt, mchehab, mcressma, mguzik, mlangsdo, nmurray, pholasek, plougher, rt-maint, rvrbovsk, slawomir, vdronov, vgoyal, williams, wmealing
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-06-15 10:48:00 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:	1332402
Bug Blocks:	1324875

Description Andrej Nemec 2016-04-07 13:22:29 UTC

A timing side channel vulnerability was discovered in the Linux Extended Verification Module (EVM). An attacker could use this to affect system integrity.

The problem exists because the vm_verify_hmac() function includes a use of memcmp(). This function is not safe to be used for comparing memory, allows timing side channel attacks; specifically a MAC forgery complexity drop from 2^128 to 2^12.  This patch changes the memcmp() to the cryptographically safe crypto_memneq().  


Upstream fix:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=613317bd212c585c20796c10afe5daaa95d4b0a1

Original bug report:

http://people.canonical.com/~ubuntu-security/cve/2016/CVE-2016-2085.html

Comment 1 Justin M. Forbes 2016-04-07 17:21:53 UTC

This does not impact Fedora as CONFIG_EVM is not enabled.

Comment 2 Wade Mealing 2016-04-29 14:34:33 UTC

Statement:

This issue does not affect the Linux kernels as shipped with Red Hat Enterprise Linux 4,5 and 6.

This issue affects the Linux kernels as shipped with Red Hat Enterprise Linux 7 and kernel-rt packages and does not plan to be addressed in a future update.