iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry
In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry device_pasid_table_teardown() zeroes the 128-bit scalable-mode context entry with context_clear_entry() while the Present bit is still set. This creates a window where the hardware can fetch a torn entry, with some fields already zeroed while Present is still set, leading to unpredictable behavior or spurious faults. The context-cache invalidation is issued only after the entry has been zeroed, and intel_pasid_free_table() then frees the PASID directory pages, so the IOMMU can keep walking a stale Present=1 entry that points at freed memory. While x86 provides strong write ordering, the compiler may reorder the two 64-bit writes to the entry, and the hardware fetch is not guaranteed to be atomic with respect to multiple CPU writes. Commit c1e4f1dccbe9d ("iommu/vt-d: Clear Present bit before tearing down context entry") fixed this exact pattern in domain_context_clear_one() and the copied-context path, but device_pasid_table_teardown() was not converted. Align it with the "Guidance to Software for Invalidations" in the VT-d spec, Section 6.5.3.3, using the same ownership handshake as the sibling fix: clear only the Present bit, flush it to the IOMMU, perform the context-cache invalidation, and only then zero the rest of the entry.
CVE-2026-74439
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-2026-74439
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": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
"lessThan": "e9e83bcfe37dc719182500dd823c03ab57d934f0",
"versionType": "git"
},
{
"status": "affected",
"version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
"lessThan": "588718101e8449605f1c7e858fecb7cfa701cdab",
"versionType": "git"
},
{
"status": "affected",
"version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
"lessThan": "7fd4077dc92b91b1b844333c0a06bb9e286db10a",
"versionType": "git"
},
{
"status": "affected",
"version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
"lessThan": "f46452c3df7a8d8a5addc0926e76ef19ea7da0a0",
"versionType": "git"
},
{
"status": "affected",
"version": "333fe86968482ca701c609af590003bcea450e8f",
"versionType": "git"
},
{
"status": "affected",
"version": "6.8.2",
"lessThan": "6.9",
"versionType": "semver"
}
],
"programFiles": [
"drivers/iommu/intel/pasid.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.9"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.9",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/iommu/intel/pasid.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-74439
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #33152 · Revision 1
- Added to Heist Feed
- Publisher date