Bug 1464473 (CVE-2017-7518)

Summary:	CVE-2017-7518 Kernel: KVM: debug exception via syscall emulation
Product:	[Other] Security Response	Reporter:	Prasad Pandit <ppandit>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	aquini, bhu, dhoward, dominik.mierzejewski, fhrbata, gansalmon, hwkernel-mgr, iboverma, ichavero, itamar, jforbes, jkacur, joelsmith, jonathan, jross, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, madhu.chinakonda, matt, mchehab, mcressma, nmurray, pbonzini, pholasek, plougher, ppandit, rt-maint, rvrbovsk, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 4.12	Doc Type:	Bug Fix
Doc Text:	A flaw was found in the way the Linux KVM module processed the trap flag(TF) bit in EFLAGS during emulation of the syscall instruction, which leads to a debug exception(#DB) being raised in the guest stack. A user/process inside a guest could use this flaw to potentially escalate their privileges inside the guest. Linux guests are not affected by this.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-08 03:15:36 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:	1464474, 1464480, 1464481, 1464482, 1464483
Bug Blocks:	1459656

Description Prasad Pandit 2017-06-23 14:05:27 UTC

Linux kernel built with the Kernel-based Virtual Machine(CONFIG_KVM) support
is vulnerable to an incorrect debug exception(#DB) error. It could occur while
emulating a syscall instruction.

A user/process inside guest could use this flaw to potentially escalate their
privileges inside guest.

Note: Linux guests are not affected.

Upstream patch:
---------------
  -> https://www.spinics.net/lists/kvm/msg151817.html

Reference:
----------
  -> https://xenbits.xen.org/xsa/advisory-204.html
  -> https://www.spinics.net/lists/kvm/msg151819.html
  -> http://www.openwall.com/lists/oss-security/2017/06/23/5
  -> https://access.redhat.com/articles/3290921

Comment 1 Prasad Pandit 2017-06-23 14:07:10 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1464474]

Comment 4 Prasad Pandit 2017-06-23 14:11:31 UTC

Statement:

This issue does not affect the versions of the kernel package as shipped with
Red Hat Enterprise Linux 5, 6 and Red Hat Enterprise MRG 2.

This issue affects the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 7. Future kernel updates for Red Hat Enterprise Linux 7
may address this issue.

Comment 9 Justin M. Forbes 2018-01-29 17:20:33 UTC

This was fixed for Fedora with the 4.11.8 stable updates.

Comment 10 errata-xmlrpc 2018-03-06 21:42:04 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:0412 https://access.redhat.com/errata/RHSA-2018:0412

Comment 11 errata-xmlrpc 2018-03-06 21:42:37 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:0395 https://access.redhat.com/errata/RHSA-2018:0395