CVE-2026-53164

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

iommu/dma: Do not try to iommu_map a 0 length region in swiotlb

iommu_dma_iova_link_swiotlb() processes a mapping that is unaligned in three

parts, the head, middle and trailer. If the middle is empty because there

are no aligned pages it will call down to iommu_map() with a 0 size

which the iommupt implementation will fail as illegal.

It then tries to do an error unwind and starts from the wrong spot

corrupting the mapping so the eventual destruction triggers a WARN_ON.

Check for 0 length and avoid mapping and use offset not 0 as the starting

point to unlink.

This is frequently triggered by using some kinds of thunderbolt NVMe

drives that trigger forced SWIOTLB for unaligned memory. NVMe seems to

pass in oddly aligned buffers for the passthrough commands from smartctl

that hit this condition.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References