On Wed, Dec 1, 2021 at 7:15 PM Vlastimil Babka <vbabka@xxxxxxx> wrote:
>
> From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
>
> KASAN accesses some slab related struct page fields so we need to convert it
> to struct slab. Some places are a bit simplified thanks to kasan_addr_to_slab()
> encapsulating the PageSlab flag check through virt_to_slab().
> When resolving object address to either a real slab or a large kmalloc, use
> struct folio as the intermediate type for testing the slab flag to avoid
> unnecessary implicit compound_head().
>
> [ vbabka@xxxxxxx: use struct folio, adjust to differences in previous patches ]
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
> Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Cc: <kasan-dev@xxxxxxxxxxxxxxxx>
> ---
> include/linux/kasan.h | 9 +++++----
> mm/kasan/common.c | 23 +++++++++++++----------
> mm/kasan/generic.c | 8 ++++----
> mm/kasan/kasan.h | 1 +
> mm/kasan/quarantine.c | 2 +-
> mm/kasan/report.c | 13 +++++++++++--
> mm/kasan/report_tags.c | 10 +++++-----
> mm/slab.c | 2 +-
> mm/slub.c | 2 +-
> 9 files changed, 42 insertions(+), 28 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index d8783b682669..fb78108d694e 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -9,6 +9,7 @@
>
> struct kmem_cache;
> struct page;
> +struct slab;
> struct vm_struct;
> struct task_struct;
>
> @@ -193,11 +194,11 @@ static __always_inline size_t kasan_metadata_size(struct kmem_cache *cache)
> return 0;
> }
>
> -void __kasan_poison_slab(struct page *page);
> -static __always_inline void kasan_poison_slab(struct page *page)
> +void __kasan_poison_slab(struct slab *slab);
> +static __always_inline void kasan_poison_slab(struct slab *slab)
> {
> if (kasan_enabled())
> - __kasan_poison_slab(page);
> + __kasan_poison_slab(slab);
> }
>
> void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
> @@ -322,7 +323,7 @@ static inline void kasan_cache_create(struct kmem_cache *cache,
> slab_flags_t *flags) {}
> static inline void kasan_cache_create_kmalloc(struct kmem_cache *cache) {}
> static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
> -static inline void kasan_poison_slab(struct page *page) {}
> +static inline void kasan_poison_slab(struct slab *slab) {}
> static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
> void *object) {}
> static inline void kasan_poison_object_data(struct kmem_cache *cache,
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 6a1cd2d38bff..7c06db78a76c 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -247,8 +247,9 @@ struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
> }
> #endif
>
> -void __kasan_poison_slab(struct page *page)
> +void __kasan_poison_slab(struct slab *slab)
> {
> + struct page *page = slab_page(slab);
> unsigned long i;
>
> for (i = 0; i < compound_nr(page); i++)
> @@ -401,9 +402,9 @@ void __kasan_kfree_large(void *ptr, unsigned long ip)
>
> void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
> {
> - struct page *page;
> + struct folio *folio;
>
> - page = virt_to_head_page(ptr);
> + folio = virt_to_folio(ptr);
>
> /*
> * Even though this function is only called for kmem_cache_alloc and
> @@ -411,12 +412,14 @@ void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
> * !PageSlab() when the size provided to kmalloc is larger than
> * KMALLOC_MAX_SIZE, and kmalloc falls back onto page_alloc.
> */
> - if (unlikely(!PageSlab(page))) {
> + if (unlikely(!folio_test_slab(folio))) {
> if (____kasan_kfree_large(ptr, ip))
> return;
> - kasan_poison(ptr, page_size(page), KASAN_FREE_PAGE, false);
> + kasan_poison(ptr, folio_size(folio), KASAN_FREE_PAGE, false);
> } else {
> - ____kasan_slab_free(page->slab_cache, ptr, ip, false, false);
> + struct slab *slab = folio_slab(folio);
> +
> + ____kasan_slab_free(slab->slab_cache, ptr, ip, false, false);
> }
> }
>
> @@ -560,7 +563,7 @@ void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
>
> void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
> {
> - struct page *page;
> + struct slab *slab;
>
> if (unlikely(object == ZERO_SIZE_PTR))
> return (void *)object;
> @@ -572,13 +575,13 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag
> */
> kasan_unpoison(object, size, false);
>
> - page = virt_to_head_page(object);
> + slab = virt_to_slab(object);
>
> /* Piggy-back on kmalloc() instrumentation to poison the redzone. */
> - if (unlikely(!PageSlab(page)))
> + if (unlikely(!slab))
> return __kasan_kmalloc_large(object, size, flags);
> else
> - return ____kasan_kmalloc(page->slab_cache, object, size, flags);
> + return ____kasan_kmalloc(slab->slab_cache, object, size, flags);
> }
>
> bool __kasan_check_byte(const void *address, unsigned long ip)
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index 5d0b79416c4e..a25ad4090615 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -330,16 +330,16 @@ DEFINE_ASAN_SET_SHADOW(f8);
>
> static void __kasan_record_aux_stack(void *addr, bool can_alloc)
> {
> - struct page *page = kasan_addr_to_page(addr);
> + struct slab *slab = kasan_addr_to_slab(addr);
> struct kmem_cache *cache;
> struct kasan_alloc_meta *alloc_meta;
> void *object;
>
> - if (is_kfence_address(addr) || !(page && PageSlab(page)))
> + if (is_kfence_address(addr) || !slab)
> return;
>
> - cache = page->slab_cache;
> - object = nearest_obj(cache, page_slab(page), addr);
> + cache = slab->slab_cache;
> + object = nearest_obj(cache, slab, addr);
> alloc_meta = kasan_get_alloc_meta(cache, object);
> if (!alloc_meta)
> return;
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index aebd8df86a1f..c17fa8d26ffe 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -265,6 +265,7 @@ bool kasan_report(unsigned long addr, size_t size,
> void kasan_report_invalid_free(void *object, unsigned long ip);
>
> struct page *kasan_addr_to_page(const void *addr);
> +struct slab *kasan_addr_to_slab(const void *addr);
>
> depot_stack_handle_t kasan_save_stack(gfp_t flags, bool can_alloc);
> void kasan_set_track(struct kasan_track *track, gfp_t flags);
> diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
> index d8ccff4c1275..587da8995f2d 100644
> --- a/mm/kasan/quarantine.c
> +++ b/mm/kasan/quarantine.c
> @@ -117,7 +117,7 @@ static unsigned long quarantine_batch_size;
>
> static struct kmem_cache *qlink_to_cache(struct qlist_node *qlink)
> {
> - return virt_to_head_page(qlink)->slab_cache;
> + return virt_to_slab(qlink)->slab_cache;
> }
>
> static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index e00999dc6499..3ad9624dcc56 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -150,6 +150,14 @@ struct page *kasan_addr_to_page(const void *addr)
> return NULL;
> }
>
> +struct slab *kasan_addr_to_slab(const void *addr)
> +{
> + if ((addr >= (void *)PAGE_OFFSET) &&
> + (addr < high_memory))
> + return virt_to_slab(addr);
> + return NULL;
> +}
> +
> static void describe_object_addr(struct kmem_cache *cache, void *object,
> const void *addr)
> {
> @@ -248,8 +256,9 @@ static void print_address_description(void *addr, u8 tag)
> pr_err("\n");
>
> if (page && PageSlab(page)) {
> - struct kmem_cache *cache = page->slab_cache;
> - void *object = nearest_obj(cache, page_slab(page), addr);
> + struct slab *slab = page_slab(page);
> + struct kmem_cache *cache = slab->slab_cache;
> + void *object = nearest_obj(cache, slab, addr);
>
> describe_object(cache, object, addr, tag);
> }
> diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c
> index 06c21dd77493..1b41de88c53e 100644
> --- a/mm/kasan/report_tags.c
> +++ b/mm/kasan/report_tags.c
> @@ -12,7 +12,7 @@ const char *kasan_get_bug_type(struct kasan_access_info *info)
> #ifdef CONFIG_KASAN_TAGS_IDENTIFY
> struct kasan_alloc_meta *alloc_meta;
> struct kmem_cache *cache;
> - struct page *page;
> + struct slab *slab;
> const void *addr;
> void *object;
> u8 tag;
> @@ -20,10 +20,10 @@ const char *kasan_get_bug_type(struct kasan_access_info *info)
>
> tag = get_tag(info->access_addr);
> addr = kasan_reset_tag(info->access_addr);
> - page = kasan_addr_to_page(addr);
> - if (page && PageSlab(page)) {
> - cache = page->slab_cache;
> - object = nearest_obj(cache, page_slab(page), (void *)addr);
> + slab = kasan_addr_to_slab(addr);
> + if (slab) {
> + cache = slab->slab_cache;
> + object = nearest_obj(cache, slab, (void *)addr);
> alloc_meta = kasan_get_alloc_meta(cache, object);
>
> if (alloc_meta) {
> diff --git a/mm/slab.c b/mm/slab.c
> index 785fffd527fe..fed55fa1b7d0 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -2605,7 +2605,7 @@ static struct slab *cache_grow_begin(struct kmem_cache *cachep,
> * page_address() in the latter returns a non-tagged pointer,
> * as it should be for slab pages.
> */
> - kasan_poison_slab(slab_page(slab));
> + kasan_poison_slab(slab);
>
> /* Get slab management. */
> freelist = alloc_slabmgmt(cachep, slab, offset,
> diff --git a/mm/slub.c b/mm/slub.c
> index 61aaaa662c5e..58f0d499a293 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1961,7 +1961,7 @@ static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
>
> slab->slab_cache = s;
>
> - kasan_poison_slab(slab_page(slab));
> + kasan_poison_slab(slab);
>
> start = slab_address(slab);
>
> --
> 2.33.1
>
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Great job with the overall struct page refactoring!
Thanks!
