6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zi Yan <ziy@xxxxxxxxxx> commit 426056efe835cf4864ccf4c328fe3af9146fc539 upstream. When dealing with hugetlb pages, manipulating struct page pointers directly can get to wrong struct page, since struct page is not guaranteed to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle it properly. A wrong or non-existing page might be tried to be grabbed, either leading to a non freeable page or kernel memory access errors. No bug is reported. It comes from code inspection. Link: https://lkml.kernel.org/r/20230913201248.452081-3-zi.yan@xxxxxxxx Fixes: 57a196a58421 ("hugetlb: simplify hugetlb handling in follow_page_mask") Signed-off-by: Zi Yan <ziy@xxxxxxxxxx> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6520,7 +6520,7 @@ struct page *hugetlb_follow_page_mask(st } } - page += ((address & ~huge_page_mask(h)) >> PAGE_SHIFT); + page = nth_page(page, ((address & ~huge_page_mask(h)) >> PAGE_SHIFT)); /* * Note that page may be a sub-page, and with vmemmap
