CVE-2026-43220

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Race Condition in Linux Kernel IOMMU AMD Driver

Publication date: 2026-05-06

Last updated on: 2026-05-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: iommu/amd: serialize sequence allocation under concurrent TLB invalidations With concurrent TLB invalidations, completion wait randomly gets timed out because cmd_sem_val was incremented outside the IOMMU spinlock, allowing CMD_COMPL_WAIT commands to be queued out of sequence and breaking the ordering assumption in wait_on_sem(). Move the cmd_sem_val increment under iommu->lock so completion sequence allocation is serialized with command queuing. And remove the unnecessary return.

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Meta Information

Published

2026-05-06

Last Modified

2026-05-17

Generated

2026-07-06

AI Q&A

2026-05-06

EPSS Evaluated

2026-07-05

NVD

CVE-2026-43220

EUVD

EUVD-2026-27780

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability exists in the Linux kernel's IOMMU AMD component, where sequence allocation for commands was not properly serialized during concurrent TLB (Translation Lookaside Buffer) invalidations.

Because the cmd_sem_val was incremented outside the IOMMU spinlock, commands that wait for completion (CMD_COMPL_WAIT) could be queued out of order, breaking the expected sequence and causing random timeouts during completion waits.

The fix involved moving the increment of cmd_sem_val inside the iommu lock to ensure serialization of command sequence allocation and removing an unnecessary return statement.

Impact Analysis

This vulnerability can cause random timeouts during command completion waits in the Linux kernel's IOMMU AMD component.

Such timeouts may lead to instability or unexpected behavior in systems relying on IOMMU for memory management and device isolation, potentially affecting system performance or reliability.

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