paravirtualized drivers incautious about shared memory contents

2015-12-1712:00:00

Xen Project

xenbits.xen.org

CVSS2

5.7

Attack Vector

LOCAL

Attack Complexity

LOW

Authentication

SINGLE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

COMPLETE

AV:L/AC:L/Au:S/C:P/I:P/A:C

CVSS3

8.2

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

HIGH

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

EPSS

0.001

Percentile

29.6%

JSON

ISSUE DESCRIPTION

The compiler can emit optimizations in the PV backend drivers which can lead to double fetch vulnerabilities. Specifically the shared memory between the frontend and backend can be fetched twice (during which time the frontend can alter the contents) possibly leading to arbitrary code execution in backend.

IMPACT

Malicious guest administrators can cause denial of service. If driver domains are not in use, the impact can be a host crash, or privilege escalation.

VULNERABLE SYSTEMS

Systems running PV or HVM guests are vulnerable.
ARM and x86 systems are vulnerable.
All OSes providing PV backends are susceptible, this includes Linux and NetBSD. By default the Linux distributions compile kernels with optimizations.