arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults
Summary
| CVE | CVE-2026-43486 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-13 16:16:51 UTC |
| Updated | 2026-05-13 16:16:51 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults contpte_ptep_set_access_flags() compared the gathered ptep_get() value against the requested entry to detect no-ops. ptep_get() ORs AF/dirty from all sub-PTEs in the CONT block, so a dirty sibling can make the target appear already-dirty. When the gathered value matches entry, the function returns 0 even though the target sub-PTE still has PTE_RDONLY set in hardware. For a CPU with FEAT_HAFDBS this gathered view is fine, since hardware may set AF/dirty on any sub-PTE and CPU TLB behavior is effectively gathered across the CONT range. But page-table walkers that evaluate each descriptor individually (e.g. a CPU without DBM support, or an SMMU without HTTU, or with HA/HD disabled in CD.TCR) can keep faulting on the unchanged target sub-PTE, causing an infinite fault loop. Gathering can therefore cause false no-ops when only a sibling has been updated: - write faults: target still has PTE_RDONLY (needs PTE_RDONLY cleared) - read faults: target still lacks PTE_AF Fix by checking each sub-PTE against the requested AF/dirty/write state (the same bits consumed by __ptep_set_access_flags()), using raw per-PTE values rather than the gathered ptep_get() view, before returning no-op. Keep using the raw target PTE for the write-bit unfold decision. Per Arm ARM (DDI 0487) D8.7.1 ("The Contiguous bit"), any sub-PTE in a CONT range may become the effective cached translation and software must maintain consistent attributes across the range. |
Risk And Classification
EPSS: 0.000230000 probability, percentile 0.069550000 (date 2026-05-28)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 4602e5757bcceb231c3a13c36c373ad4a750eddb 05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0 git | Not specified |
| CNA | Linux | Linux | affected 4602e5757bcceb231c3a13c36c373ad4a750eddb 6f92a7a8b48a523f910ef25dd83808710724f59b git | Not specified |
| CNA | Linux | Linux | affected 4602e5757bcceb231c3a13c36c373ad4a750eddb 09d620555e59768776090073a2c59d2bc8506eb3 git | Not specified |
| CNA | Linux | Linux | affected 4602e5757bcceb231c3a13c36c373ad4a750eddb 97c5550b763171dbef61e6239cab372b9f9cd4a2 git | Not specified |
| CNA | Linux | Linux | affected 6.9 | Not specified |
| CNA | Linux | Linux | unaffected 6.9 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.78 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.19 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.19.9 6.19.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/6f92a7a8b48a523f910ef25dd83808710724f59b | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/97c5550b763171dbef61e6239cab372b9f9cd4a2 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/09d620555e59768776090073a2c59d2bc8506eb3 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.