6.6-stable review patch. If anyone has any objections, please let me know.
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From: Zi Yan ziy@nvidia.com
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@sent.com Fixes: 57a196a58421 ("hugetlb: simplify hugetlb handling in follow_page_mask") Signed-off-by: Zi Yan ziy@nvidia.com Reviewed-by: Muchun Song songmuchun@bytedance.com Cc: David Hildenbrand david@redhat.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Mike Kravetz mike.kravetz@oracle.com Cc: Mike Rapoport (IBM) rppt@kernel.org Cc: Thomas Bogendoerfer tsbogend@alpha.franken.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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