{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39961", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.149Z", "datePublished": "2025-10-09T12:13:22.029Z", "dateUpdated": "2026-08-05T12:06:29.974Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:06:29.974Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd/pgtbl: Fix possible race while increase page table level\n\nThe AMD IOMMU host page table implementation supports dynamic page table levels\n(up to 6 levels), starting with a 3-level configuration that expands based on\nIOVA address. The kernel maintains a root pointer and current page table level\nto enable proper page table walks in alloc_pte()/fetch_pte() operations.\n\nThe IOMMU IOVA allocator initially starts with 32-bit address and onces its\nexhuasted it switches to 64-bit address (max address is determined based\non IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU\ndriver increases page table level.\n\nBut in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads\npgtable->[root/mode] without lock. So its possible that in exteme corner case,\nwhen increase_address_space() is updating pgtable->[root/mode], fetch_pte()\nreads wrong page table level (pgtable->mode). It does compare the value with\nlevel encoded in page table and returns NULL. This will result is\niommu_unmap ops to fail and upper layer may retry/log WARN_ON.\n\nCPU 0 CPU 1\n------ ------\nmap pages unmap pages\nalloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte()\n pgtable->root = pte (new root value)\n READ pgtable->[mode/root]\n\t\t\t\t\t Reads new root, old mode\n Updates mode (pgtable->mode += 1)\n\nSince Page table level updates are infrequent and already synchronized with a\nspinlock, implement seqcount to enable lock-free read operations on the read path." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The race is reached through local DMA-mapping activity — either VFIO/iommufd map/unmap ioctls or ordinary syscall-driven I/O that exercises dma_map/dma_unmap on a device behind the AMD IOMMU. No network protocol handler processes remote data on this path.\nAC:L - The attacker controls both sides of the race: one thread issues a high-IOVA map that forces increase_address_space() while other threads issue concurrent unmaps on the same domain, and the attempt can be repeated indefinitely because each newly created protection_domain restarts at PAGE_MODE_3_LEVEL. No condition depends on state outside the attacker's influence, and CONFIG_AMD_IOMMU with v1 host page tables is the default on all AMD x86_64 systems.\nPR:L - An unprivileged local user can drive the concurrent map/unmap traffic that exhausts the 32-bit IOVA space and triggers the page-table level increase; in device-assignment deployments the VFIO/iommufd ioctl path is exercised by an unprivileged QEMU process. No root or capability in the init namespace is required.\nUI:N - The race is triggered entirely by the attacker's own concurrent DMA map/unmap operations. No victim action is needed.\nS:C - A silently-failed iommu_v1_unmap_pages() leaves a live IOMMU translation after __iommu_dma_unmap() frees the IOVA and the driver recycles the buffer, so a DMA-capable device — including a guest-controlled assigned device — retains read/write access to host physical memory it must no longer reach. This is an IOMMU/DMA containment bypass that crosses out of the kernel's own security authority.\nC:H - The stale mapping lets the device read physical pages that have been returned to the allocator and refilled with arbitrary kernel or other-tenant data, giving an unbounded read primitive over reused memory; the torn read in alloc_pte() can additionally alias a mapping onto another buffer in the domain.\nI:H - The same stale or mis-installed translation is writable, so the device can DMA arbitrary attacker-chosen data into freed-and-reused kernel memory, yielding a write primitive suitable for control-flow hijacking. The corruption is invisible to the kernel because the unmap was reported as complete.\nA:H - The failed unmap immediately produces WARN_ON splats in __iommu_dma_unmap()/iommu_unmap_nofail() (a panic with panic_on_warn), and the resulting DMA into recycled memory or the mis-built page-table subtree causes IO page faults, page-table page leaks, and kernel crashes." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/iommu/amd/amd_iommu_types.h", "drivers/iommu/amd/io_pgtable.c" ], "versions": [ { "version": "754265bcab78a9014f0f99cd35e0d610fcd7dfa7", "lessThan": "075abf0b1a958acfbea2435003d228e738e90346", "status": "affected", "versionType": "git" }, { "version": "754265bcab78a9014f0f99cd35e0d610fcd7dfa7", "lessThan": "cd92c8ab336c3a633d46e6f35ebcd3509ae7db3b", "status": "affected", "versionType": "git" }, { "version": "754265bcab78a9014f0f99cd35e0d610fcd7dfa7", "lessThan": "7d462bdecb7d9c32934dab44aaeb7ea7d73a27a2", "status": "affected", "versionType": "git" }, { "version": "754265bcab78a9014f0f99cd35e0d610fcd7dfa7", "lessThan": "1e56310b40fd2e7e0b9493da9ff488af145bdd0c", "status": "affected", "versionType": "git" }, { "version": "6fb92f18555a7b8e085267d513612dc0ff9a5360", "status": "affected", "versionType": "git" }, { "version": "b15bf74405faa1a65025eb8a6eb337e140e5250a", "status": "affected", "versionType": "git" }, { "version": "0d50f7b1e8c80a8c20db5049e269468c059b0378", "status": "affected", "versionType": "git" }, { "version": "785ca708a908b9c596ede852470ba28b8dc3e40b", "status": "affected", "versionType": "git" }, { "version": "4.9.194", "lessThan": "4.10", "status": "affected", "versionType": "semver" }, { "version": "4.14.146", "lessThan": "4.15", "status": "affected", "versionType": "semver" }, { "version": "4.19.75", "lessThan": "4.20", "status": "affected", "versionType": "semver" }, { "version": "5.2.17", "lessThan": "5.3", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/iommu/amd/amd_iommu_types.h", "drivers/iommu/amd/io_pgtable.c" ], "versions": [ { "version": "5.3", "status": "affected" }, { "version": "0", "lessThan": "5.3", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.108", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.49", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.9", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.6.108" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.12.49" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.16.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.17" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9.194" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14.146" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19.75" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.2.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/075abf0b1a958acfbea2435003d228e738e90346" }, { "url": "https://git.kernel.org/stable/c/cd92c8ab336c3a633d46e6f35ebcd3509ae7db3b" }, { "url": "https://git.kernel.org/stable/c/7d462bdecb7d9c32934dab44aaeb7ea7d73a27a2" }, { "url": "https://git.kernel.org/stable/c/1e56310b40fd2e7e0b9493da9ff488af145bdd0c" } ], "title": "iommu/amd/pgtbl: Fix possible race while increase page table level", "x_generator": { "engine": "bippy-1.2.0" } } } }