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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-90243
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:17:20 UTC
Updated2026-09-18 18:17:50 UTC
DescriptionIn 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 6.5.3.3 ("Guidance to Software for Invalidations"): clear only the Present bit, flush it out to the IOMMU, perform the invalidations, and only then zero the remainder of the entry.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS: 0.001610000 probability, percentile 0.057460000 (date 2026-09-21)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.1HIGHCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1CNADECLARED8.1HIGHCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected c7191984e5aade540f1a3845a116537c89572655 97750a8dce79c1a9b2b2d2a020b61b800141996c git Not specified
CNA Linux Linux affected c7191984e5aade540f1a3845a116537c89572655 3c88cfedc7768b1ae2dc7ddc71547ae9a1aaff7d git Not specified
CNA Linux Linux affected c7191984e5aade540f1a3845a116537c89572655 6b822d18c33af9d1e16a8e5e6aa6e656987b09de git Not specified
CNA Linux Linux affected c7191984e5aade540f1a3845a116537c89572655 f532c57985b1a7d6b7e37e05506b46d413e5cca4 git Not specified
CNA Linux Linux affected 6.12 Not specified
CNA Linux Linux unaffected 6.12 semver Not specified
CNA Linux Linux unaffected 6.12.110 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.52 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/97750a8dce79c1a9b2b2d2a020b61b800141996c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3c88cfedc7768b1ae2dc7ddc71547ae9a1aaff7d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6b822d18c33af9d1e16a8e5e6aa6e656987b09de 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f532c57985b1a7d6b7e37e05506b46d413e5cca4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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