On 13 Sep 2023, at 16:12, Zi Yan wrote:

From: Zi Yan ziy@nvidia.com

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.

Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc") Cc: stable@vger.kernel.org Signed-off-by: Zi Yan ziy@nvidia.com Reviewed-by: Muchun Song songmuchun@bytedance.com

---

mm/cma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/cma.c b/mm/cma.c index da2967c6a223..2b2494fd6b59 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -505,7 +505,7 @@ 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) {

-- 2.40.1

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.

-- Best Regards, Yan, Zi