With tag based KASAN page_address() looks at the page flags to see whether the resulting pointer needs to have a tag set. Since we don't want to set a tag when page_address() is called on SLAB pages, we call page_kasan_tag_reset() in kasan_poison_slab(). However in allocate_slab() page_address() is called before kasan_poison_slab(). Fix it by changing the order.
Signed-off-by: Andrey Konovalov <[email protected]> --- mm/slub.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 4a3d7686902f..ce874a5c9ee7 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1642,12 +1642,15 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) if (page_is_pfmemalloc(page)) SetPageSlabPfmemalloc(page); + kasan_poison_slab(page); + start = page_address(page); - if (unlikely(s->flags & SLAB_POISON)) + if (unlikely(s->flags & SLAB_POISON)) { + metadata_access_enable(); memset(start, POISON_INUSE, PAGE_SIZE << order); - - kasan_poison_slab(page); + metadata_access_disable(); + } shuffle = shuffle_freelist(s, page); -- 2.20.1.791.gb4d0f1c61a-goog
