From 5a2768b9de0cc4a586dd0fe228d5b1e8cd019a5e Mon Sep 17 00:00:00 2001 From: Zi Yan Date: Wed, 13 Sep 2023 16:12:44 -0400 Subject: [PATCH] mm/cma: use nth_page() in place of direct struct page manipulation commit 2e7cfe5cd5b6b0b98abf57a3074885979e187c1c upstream. Patch series "Use nth_page() in place of direct struct page manipulation", v3. On SPARSEMEM without VMEMMAP, struct page is not guaranteed to be contiguous, since each memory section's memmap might be allocated independently. hugetlb pages can go beyond a memory section size, thus direct struct page manipulation on hugetlb pages/subpages might give wrong struct page. Kernel provides nth_page() to do the manipulation properly. Use that whenever code can see hugetlb pages. This patch (of 5): 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. Without the fix, page_kasan_tag_reset() could reset wrong page tags, causing a wrong kasan result. No related bug is reported. The fix comes from code inspection. Link: https://lkml.kernel.org/r/20230913201248.452081-1-zi.yan@sent.com Link: https://lkml.kernel.org/r/20230913201248.452081-2-zi.yan@sent.com Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc") Signed-off-by: Zi Yan Reviewed-by: Muchun Song Cc: David Hildenbrand Cc: Matthew Wilcox (Oracle) Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Thomas Bogendoerfer Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/cma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/cma.c b/mm/cma.c index 4a978e0..30b6ca3 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -500,7 +500,7 @@ struct page *cma_alloc(struct cma *cma, unsigned long count, */ if (page) { for (i = 0; i < count; i++) - page_kasan_tag_reset(page + i); + page_kasan_tag_reset(nth_page(page, i)); } if (ret && !no_warn) { -- 2.7.4