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

Summary

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.

Timeline

1. May 27, 2026, 12:18 PM UTCCVE published
2. Oct 16, 2026, 3:18 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 19, 2026, 7:26 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 7543ee63e8113aa34b07df3b16b3b9d2c5f73939 · fixed in 4718007870547e1efebbdd6745d9fce58f008fef; From 7543ee63e8113aa34b07df3b16b3b9d2c5f73939 · fixed in 66a7aff480a82b8642b3991fed5fdc9780022157; From 7543ee63e8113aa34b07df3b16b3b9d2c5f73939 · fixed in c3b1edea3791fa91ab7032faa90355913ad9451b

• Linux Linux

  6.13

• KernelLinux

  From 6.13.0 · fixed in 6.18.39; From 6.19.0 · fixed in 6.19.4

References 3