cbcvebase.
CVE-2025-39961
published 2025-10-09

CVE-2025-39961: 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…

PriorityP419medium4.7CVSS 3.1
AVLACHPRLUINSUCNINAH
EPSS
0.11%
1.3th percentile
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.

Affected

35 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.16.9-1 (forky)linux 6.16.9-1 (forky)
linuxlinux
linuxlinux
linuxlinux
linuxlinux
linuxlinux
linuxlinux>= 4.14.146 < 4.154.15
linuxlinux>= 4.19.75 < 4.204.20
linuxlinux>= 4.9.194 < 4.104.10
linuxlinux>= 5.2.17 < 5.35.3
linuxlinux>= 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 < 075abf0b1a958acfbea2435003d228e738e90346075abf0b1a958acfbea2435003d228e738e90346
linuxlinux>= 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 < cd92c8ab336c3a633d46e6f35ebcd3509ae7db3bcd92c8ab336c3a633d46e6f35ebcd3509ae7db3b
linuxlinux>= 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 < 7d462bdecb7d9c32934dab44aaeb7ea7d73a27a27d462bdecb7d9c32934dab44aaeb7ea7d73a27a2
linuxlinux>= 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 < 1e56310b40fd2e7e0b9493da9ff488af145bdd0c1e56310b40fd2e7e0b9493da9ff488af145bdd0c
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.12.57-16.12.57-1
linuxlinux_kernel>= 0 < 6.16.9-16.16.9-1
linuxlinux_kernel>= 0 < 6.8.0-106.1066.8.0-106.106

CVSS provenance

nvdv3.14.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
osv4.7MEDIUM
vendor_ubuntu7.8HIGH
vendor_msrc5.8MEDIUM
vendor_debian4.7MEDIUM
vendor_redhat4.7MEDIUM
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