IOMMU Vulnerability in Linux Kernel Affects Intel Hardware Handling

CVE-2026-74439

What is CVE-2026-74439?

This vulnerability arises from improper handling of the Present bit in the Linux kernel's IOMMU subsystem, specifically in the device PASID table teardown process. When the device_pasid_table_teardown() function zeroes a scalable-mode context entry without first clearing the Present bit, it creates a race condition that allows the hardware to fetch a partially zeroed entry. This can lead to unpredictable behavior and faults, as the invalid entries may point to freed memory. A fix was implemented to ensure that the Present bit is cleared before any other actions are taken, thereby aligning with best practices outlined in the VT-d specification to prevent these issues.

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