{"id":"CVE-2026-89908","summary":"LoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY\n\nkvm_arch_prepare_memory_region() computes new-\u003earch.flags, i.e. whether\na memslot is KVM_MEM_HUGEPAGE_CAPABLE or KVM_MEM_HUGEPAGE_INCAPABLE,\nonly for KVM_MR_CREATE and KVM_MR_MOVE, and returns early for every\nother change. But the generic code allocates a zeroed memslot for every\nchange and never copies old-\u003earch, so after a KVM_MR_FLAGS_ONLY update,\ne.g. toggling KVM_MEM_LOG_DIRTY_PAGES for live migration, the active\nmemslot has arch.flags == 0.\n\nWith both flags clear, fault_supports_huge_mapping() falls through to\nthe alignment check on the HVA range alone, which no longer verifies\nthat the GPA and HVA have the same offset within a PMD. A memslot that\nwas marked KVM_MEM_HUGEPAGE_INCAPABLE because of a GPA/HVA offset\nmismatch can then be mapped with PMD entries on read faults, and since\nkvm_map_page() aligns the gfn and the pfn independently, the guest ends\nup accessing the wrong host pages, exactly the \"d -\u003e f, e -\u003e g\" case\ndescribed in the comment above the check.\n\nCarry the arch flags over from the old memslot for KVM_MR_FLAGS_ONLY,\nas the GPA, HVA and size are guaranteed to be unchanged for that case.","modified":"2026-09-17T03:46:55.549439281Z","published":"2026-09-16T10:32:06.599Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89908.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/27a9bfee3bbcb3cabb77797354f07e0e44e49831"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4e4dbc341b1581dc512b85d98b768373b0398366"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89908.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89908"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c"},{"fixed":"7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8"},{"fixed":"4e4dbc341b1581dc512b85d98b768373b0398366"},{"fixed":"bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba"},{"fixed":"27a9bfee3bbcb3cabb77797354f07e0e44e49831"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89908.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.8.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89908.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}