CVE-2026-64302 in Linux
Tóm tắt
Bởi MITRE • 25/07/2026
In the Linux kernel, the following vulnerability has been resolved:
x86/mm: Fix freeing of PMD-sized vmemmap pages
Commit bf9e4e30f353 ("x86/mm: use pagetable_free()"), switched from freeing non-boot page tables through __free_pages() to pagetable_free().
However, the function is also called to free vmemmap pages.
Given that vmemmap pages are not page tables, already the page_ptdesc(page) is wrong. But worse, pagetable_free() calls:
__free_pages(page, compound_order(page));
Since vmemmap pages are not compound pages (see vmemmap_alloc_block()) -- except for HVO, which doesn't apply here -- only first page of a PMD-sized vmemmap page is freed, leaking the other ones.
Fix it by properly decoupling pagetable and vmemmap freeing. free_pagetable() no longer has to mess with SECTION_INFO, as only the vmemmap is marked like that in register_page_bootmem_memmap().
The indentation in remove_pmd_table() is messed up. Fix that while touching it.
Bootmem info handling will soon be fixed up. For now, handle it similar to free_pagetable(), just avoiding the ifdef.
[ dhansen: changelog munging. More imperative voice ]
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