CVE-2026-45945iommu/vt-d: Fix race condition during PASID entry replacement

Official description

In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Fix race condition during PASID entry replacement The Intel VT-d PASID table entry is 512 bits (64 bytes). When replacing an active PASID entry (e.g., during domain replacement), the current implementation calculates a new entry on the stack and copies it to the table using a single structure assignment. struct pasid_entry *pte, new_pte; pte = intel_pasid_get_entry(dev, pasid); pasid_pte_config_first_level(iommu, &new_pte, ...); *pte = new_pte; Because the hardware may fetch the 512-bit PASID entry in multiple 128-bit chunks, updating the entire entry while it is active (Present bit set) risks a "torn" read. In this scenario, the IOMMU hardware could observe an inconsistent state — partially new data and partially old data — leading to unpredictable behavior or spurious faults. Fix this by removing the unsafe "replace" helpers and following the "clear-then-update" flow, which ensures the Present bit is cleared and the required invalidation handshake is completed before the new configuration is applied.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/4718007870547e1efebbdd6745d9fce58f008fef
• https://git.kernel.org/stable/c/66a7aff480a82b8642b3991fed5fdc9780022157
• https://git.kernel.org/stable/c/c3b1edea3791fa91ab7032faa90355913ad9451b