Currently, kasan_free_nondeferred_pages()->kasan_free_pages() is called after debug_pagealloc_unmap_pages(). This causes a crash when debug_pagealloc is enabled, as HW_TAGS KASAN can't set tags on an unmapped page.

This patch puts kasan_free_nondeferred_pages() before debug_pagealloc_unmap_pages() and arch_free_page(), which can also make the page unavailable.

Fixes: 94ab5b61ee16 ("kasan, arm64: enable CONFIG_KASAN_HW_TAGS") Cc: stable@vger.kernel.org Signed-off-by: Andrey Konovalov andreyknvl@google.com

---

Changes v2->v3: - Rebase onto mainline.

--- mm/page_alloc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3e4b29ee2b1e..c89ee1ba7034 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1281,6 +1281,12 @@ static __always_inline bool free_pages_prepare(struct page *page,

kernel_poison_pages(page, 1 << order);

+ /* + * With hardware tag-based KASAN, memory tags must be set before the + * page becomes unavailable via debug_pagealloc or arch_free_page. + */ + kasan_free_nondeferred_pages(page, order); + /* * arch_free_page() can make the page's contents inaccessible. s390 * does this. So nothing which can access the page's contents should @@ -1290,8 +1296,6 @@ static __always_inline bool free_pages_prepare(struct page *page,

debug_pagealloc_unmap_pages(page, 1 << order);

- kasan_free_nondeferred_pages(page, order); - return true; }