Description
In the Linux kernel, the following vulnerability has been resolved: LoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY kvm_arch_prepare_memory_region() computes new->arch.flags, i.e. whether a memslot is KVM_MEM_HUGEPAGE_CAPABLE or KVM_MEM_HUGEPAGE_INCAPABLE, only for KVM_MR_CREATE and KVM_MR_MOVE, and returns early for every other change. But the generic code allocates a zeroed memslot for every change and never copies old->arch, so after a KVM_MR_FLAGS_ONLY update, e.g. toggling KVM_MEM_LOG_DIRTY_PAGES for live migration, the active memslot has arch.flags == 0. With both flags clear, fault_supports_huge_mapping() falls through to the alignment check on the HVA range alone, which no longer verifies that the GPA and HVA have the same offset within a PMD. A memslot that was marked KVM_MEM_HUGEPAGE_INCAPABLE because of a GPA/HVA offset mismatch can then be mapped with PMD entries on read faults, and since kvm_map_page() aligns the gfn and the pfn independently, the guest ends up accessing the wrong host pages, exactly the "d -> f, e -> g" case described in the comment above the check. Carry the arch flags over from the old memslot for KVM_MR_FLAGS_ONLY, as the GPA, HVA and size are guaranteed to be unchanged for that case.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c to < 7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8affected7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c to < 4e4dbc341b1581dc512b85d98b768373b0398366affected7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c to < bc7a6849b4395f45a602db91b0fb2fb2e9ed4bbaaffected7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c to < 27a9bfee3bbcb3cabb77797354f07e0e44e49831affected
Linux Linux
Default version status: affected
6.8affected0 to < 6.8unaffected6.12.110 to ≤ 6.12.*unaffected6.18.51 to ≤ 6.18.*unaffected7.2.5 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected