CVE-2021-28692

Name of the Vulnerable Software and Affected Versions Xen (affected versions not specified)

Description The issue is related to inappropriate x86 IOMMU timeout detection and handling. IOMMUs process commands 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, and 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. However, the course of action upon a perceived timeout actually being detected is inappropriate, potentially causing guests to be marked as crashed on Intel hardware or higher layer callers to continue as if the IOMMU operation succeeded on AMD hardware.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.