CVE-2025-39961High· 8.8▾ TwilightIn the Linux kernel, the following vulnerability has been resolved: iommu/amd/pgtbl: Fix possible race while increase page table level The AMD IOMMU host page table implementation supports dynamic page table levels (up to 6 levels), st…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 48.4 · likelihood 0 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Oct 15.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Last analysed / modified upstream
0.1%
0.1% → 0.1%
In the Linux kernel, the following vulnerability has been resolved:
iommu/amd/pgtbl: Fix possible race while increase page table level
The AMD IOMMU host page table implementation supports dynamic page table levels (up to 6 levels), starting with a 3-level configuration that expands based on IOVA address. The kernel maintains a root pointer and current page table level to enable proper page table walks in alloc_pte()/fetch_pte() operations.
The IOMMU IOVA allocator initially starts with 32-bit address and onces its exhuasted it switches to 64-bit address (max address is determined based on IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU driver increases page table level.
But in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads pgtable->[root/mode] without lock. So its possible that in exteme corner case, when increase_address_space() is updating pgtable->[root/mode], fetch_pte() reads wrong page table level (pgtable->mode). It does compare the value with level encoded in page table and returns NULL. This will result is iommu_unmap ops to fail and upper layer may retry/log WARN_ON.
CPU 0 CPU 1
map pages unmap pages alloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte() pgtable->root = pte (new root value) READ pgtable->[mode/root] Reads new root, old mode Updates mode (pgtable->mode += 1)
Since Page table level updates are infrequent and already synchronized with a spinlock, implement seqcount to enable lock-free read operations on the read path.
Linux >= 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 < 075abf0b1a958acfbea2435003d228e738e90346Linux >= 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 < cd92c8ab336c3a633d46e6f35ebcd3509ae7db3bLinux >= 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 < 7d462bdecb7d9c32934dab44aaeb7ea7d73a27a2Linux >= 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 < 1e56310b40fd2e7e0b9493da9ff488af145bdd0cLinux 6fb92f18555a7b8e085267d513612dc0ff9a5360Linux b15bf74405faa1a65025eb8a6eb337e140e5250aLinux 0d50f7b1e8c80a8c20db5049e269468c059b0378Linux 785ca708a908b9c596ede852470ba28b8dc3e40bLinux >= 4.9.194 < 4.10Linux >= 4.14.146 < 4.15Linux >= 4.19.75 < 4.20Linux >= 5.2.17 < 5.3Linux 5.3Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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