{"id":"CVE-2026-89908","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89908","summary":"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->arch.flags,…","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->arch.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->arch, 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 -> f, e -> 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.","published":"2026-09-16T11:16:59.807","modified":"2026-09-16T11:16:59.807","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":null,"references":[{"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"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-09-16T11:16:59.807"}}