CVE-2026-90243

/// Technical description

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

iommu/vt-d: Clear Present bit before tearing down copied context entry

copied_context_tear_down() zeroes the 128-bit context entry with

context_clear_entry() while the Present bit is still set, and only then

issues the context-cache and IOTLB invalidations. This leaves a window

in which hardware can fetch a torn entry, with some fields already zeroed

while Present is still set, leading to unpredictable behaviour or

spurious faults. While x86 provides strong write ordering, the compiler

may reorder the writes to the two 64-bit halves of the entry, and the

hardware fetch is not guaranteed to be atomic with respect to multiple

CPU writes.

There is no cacheline flush before the invalidation either, so on an

IOMMU without coherent access to the context table the zeroed entry may

not be visible to hardware at the point the invalidation is submitted.

Apply the same ownership handshake described in the VT-d spec, Section

/// 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