Linux Kernel IOMMU/AMD Concurrent TLB Invalidations Serialization Vulnerability

A vulnerability in the Linux kernel's IOMMU AMD handling has been addressed. The issue arose from concurrent TLB invalidations, which caused completion waits to time out randomly. This was due to the command semaphore value being incremented outside of the IOMMU spinlock, allowing completion wait commands to be queued out of order. The vulnerability affected the Linux kernel stable tree.

Impact

The vulnerability could lead to improper sequencing of IOMMU commands, potentially causing timeouts in completion waits and disrupting the expected command processing order.

Reproduction

The vulnerability can be reproduced by initiating concurrent TLB invalidations in an environment where the Linux kernel IOMMU AMD handling is active. This will cause the command semaphore value to be incremented out of sequence, leading to timed-out completion waits.

Remediation

Users can update to the latest version of the Linux kernel stable tree, where this vulnerability has been fixed.