GLSA 201703-07: Xen: Privilege Escalation

http://security.gentoo.org/

Severity:	normal
Title:	Xen: Privilege Escalation
Date:	03/28/2017
Bugs:	#609120
ID:	201703-07

Synopsis

A vulnerability in Xen's bundled QEMU version might allow privilege escalation.

Background

Xen is a bare-metal hypervisor.

Affected packages

Package	Vulnerable	Unaffected	Architecture(s)
app-emulation/xen-tools	< 4.7.1-r8	>= 4.7.1-r8	All supported architectures

Description

In CIRRUS_BLTMODE_MEMSYSSRC mode the bitblit copy routine cirrus_bitblt_cputovideo fails to check wethehr the specified memory region is safe.

Impact

A local attacker could potentially execute arbitrary code with privileges of Xen (QEMU) process on the host, gain privileges on the host system, or cause a Denial of Service condition.

Workaround

Running guests in Paravirtualization (PV) mode, or running guests in Hardware-assisted virtualizion (HVM) utilizing stub domains mitigate the issue.

Running HVM guests with the device model in a stubdomain will mitigate the issue.

Changing the video card emulation to stdvga (stdvga=1, vga=”stdvga”, in the xl domain configuration) will avoid the vulnerability.

Resolution

All Xen Tools users should upgrade to the latest version:

      # emerge --sync
      # emerge --ask --oneshot --verbose
      ">=app-emulation/xen-tools-4.7.1-r8"

References

CVE-2017-2620

Availability

This GLSA and any updates to it are available for viewing at the Gentoo Security Website: http://security.gentoo.org/glsa/glsa-201703-07.xml

Concerns?

Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users machines is of utmost importance to us. Any security concerns should be addressed to security@gentoo.org or alternatively, you may file a bug at https://bugs.gentoo.org.