CVE ID : CVE-2025-39961<\/p>\n
Published : Oct. 9, 2025, 12:13 p.m. | 24\u00a0minutes ago<\/p>\n
Description : In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
iommu\/amd\/pgtbl: Fix possible race while increase page table level<\/p>\n
The 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.<\/p>\n
The 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.<\/p>\n
But 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.<\/p>\n
CPU 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)<\/p>\n
Since Page table level updates are infrequent and already synchronized with a
\nspinlock, implement seqcount to enable lock-free read operations on the read path.<\/p>\n
Severity: 0.0 | NA<\/p>\n
Visit the link for more details, such as CVSS details, affected products, timeline, and more…\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"
CVE ID : CVE-2025-39961 Published : Oct. 9, 2025, 12:13 p.m. | 24\u00a0minutes ago Description : 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 …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[],"class_list":["post-71293","post","type-post","status-publish","format-standard","hentry","category-vulnerability"],"_links":{"self":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/71293","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/comments?post=71293"}],"version-history":[{"count":0,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/71293\/revisions"}],"wp:attachment":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/media?parent=71293"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/categories?post=71293"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/tags?post=71293"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}