Xen Inappropriate x86 IOMMU Timeout Detection / Handling (XSA-372)

high Nessus Plugin ID 152208

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Synopsis

The remote Xen hypervisor installation is missing a security update.

Description

According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a vulnerability due to inappropriate x86 IOMMU timeout detection / handling IOMMUs process commands issued to them in parallel with the operation of the CPU(s) issuing such commands. In the current implementation in Xen, asynchronous notification of the completion of such commands is not used. Instead, the issuing CPU spin-waits for the completion of the most recently issued command(s). Some of these waiting loops try to apply a timeout to fail overly-slow commands.
The course of action upon a perceived timeout actually being detected is inappropriate: - on Intel hardware guests which did not originally cause the timeout may be marked as crashed, - on AMD hardware higher layer callers would not be notified of the issue, making them continue as if the IOMMU operation succeeded.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Apply the appropriate patch according to the vendor advisory.

Plugin Details

Severity: High

ID: 152208

File Name: xen_server_XSA-373.nasl

Version: 1.4

Type: local

Family: Misc.

Published: 8/4/2021

Updated: 1/26/2022

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.2

CVSS v2

Risk Factor: Medium

Base Score: 5.6

Temporal Score: 4.1

Vector: CVSS2#AV:L/AC:L/Au:N/C:P/I:N/A:C

CVSS Score Source: CVE-2021-28692

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.2

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:xen:xen

Required KB Items: Settings/ParanoidReport, installed_sw/Xen Hypervisor

Exploit Ease: No known exploits are available

Patch Publication Date: 6/30/2021

Vulnerability Publication Date: 6/30/2021

Reference Information

CVE: CVE-2021-28692

IAVB: 2021-B-0044-S

Detections

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