iommu/vt-d: Clear Present bit before tearing down PASID entry
In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Clear Present bit before tearing down PASID entry The Intel VT-d Scalable Mode PASID table entry consists of 512 bits (64 bytes). When tearing down an entry, the current implementation zeros the entire 64-byte structure immediately using multiple 64-bit writes. Since the IOMMU hardware may fetch these 64 bytes using multiple internal transactions (e.g., four 128-bit bursts), updating or zeroing the entire entry while it is active (P=1) risks a "torn" read. If a hardware fetch occurs simultaneously with the CPU zeroing the entry, the hardware could observe an inconsistent state, leading to unpredictable behavior or spurious faults. Follow the "Guidance to Software for Invalidations" in the VT-d spec (Section 6.5.3.3) by implementing the recommended ownership handshake: 1. Clear only the 'Present' (P) bit of the PASID entry. 2. Use a dma_wmb() to ensure the cleared bit is visible to hardware before proceeding. 3. Execute the required invalidation sequence (PASID cache, IOTLB, and Device-TLB flush) to ensure the hardware has released all cached references. 4. Only after the flushes are complete, zero out the remaining fields of the PASID entry. Also, add a dma_wmb() in pasid_set_present() to ensure that all other fields of the PASID entry are visible to the hardware before the Present bit is set.
CVE-2026-45894
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-45894
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15",
"lessThan": "c36b0515c6445bd137ec8ad86ef5470c45d6e4bf",
"versionType": "git"
},
{
"status": "affected",
"version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15",
"lessThan": "a84d30e8d2bacd21782a6481158b7c9c552f4868",
"versionType": "git"
},
{
"status": "affected",
"version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15",
"lessThan": "821807c167b7b48a41b95b6607c6b9f97600f7d9",
"versionType": "git"
},
{
"status": "affected",
"version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15",
"lessThan": "949d71666e9dd19f21e7b4b53a88cd2c5b902858",
"versionType": "git"
},
{
"status": "affected",
"version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15",
"lessThan": "75ed00055c059dedc47b5daaaa2f8a7a019138ff",
"versionType": "git"
}
],
"programFiles": [
"drivers/iommu/intel/pasid.c",
"drivers/iommu/intel/pasid.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.0"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.75",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.14",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "6.19.4",
"versionType": "semver",
"lessThanOrEqual": "6.19.*"
},
{
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/iommu/intel/pasid.c",
"drivers/iommu/intel/pasid.h"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-45894
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #46310 · Revision 1
- Added to Heist Feed
- Publisher date