Since kasan_kmalloc() always follows kasan_slab_alloc(), there's no need to reunpoison the object data, only to poison the redzone. This requires changing kasan annotation for early SLUB cache to kasan_slab_alloc(). Otherwise kasan_kmalloc() doesn't untag the object. This doesn't do any functional changes, as kmem_cache_node->object_size is equal to sizeof(struct kmem_cache_node). Similarly for kasan_krealloc(), as it's called after ksize(), which already unpoisoned the object, there's no need to do it again. Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Link: https://linux-review.googlesource.com/id/I4083d3b55605f70fef79bca9b90843c4390296f2 --- mm/kasan/common.c | 31 +++++++++++++++++++++---------- mm/slub.c | 3 +-- 2 files changed, 22 insertions(+), 12 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index c5ec60e1a4d2..a581937c2a44 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -360,8 +360,14 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object, if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS)) tag = assign_tag(cache, object, false, keep_tag); - /* Tag is ignored in set_tag without CONFIG_KASAN_SW/HW_TAGS */ - kasan_unpoison_memory(set_tag(object, tag), size); + /* + * Don't unpoison the object when keeping the tag. Tag is kept for: + * 1. krealloc(), and then the memory has already been unpoisoned via ksize(); + * 2. kmalloc(), and then the memory has already been unpoisoned by kasan_kmalloc(). + * Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS. + */ + if (!keep_tag) + kasan_unpoison_memory(set_tag(object, tag), size); kasan_poison_memory((void *)redzone_start, redzone_end - redzone_start, KASAN_KMALLOC_REDZONE); @@ -384,10 +390,9 @@ void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object } EXPORT_SYMBOL(__kasan_kmalloc); -void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size, - gfp_t flags) +static void * __must_check ____kasan_kmalloc_large(struct page *page, const void *ptr, + size_t size, gfp_t flags, bool realloc) { - struct page *page; unsigned long redzone_start; unsigned long redzone_end; @@ -397,18 +402,24 @@ void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size, if (unlikely(ptr == NULL)) return NULL; - page = virt_to_page(ptr); - redzone_start = round_up((unsigned long)(ptr + size), - KASAN_GRANULE_SIZE); + redzone_start = round_up((unsigned long)(ptr + size), KASAN_GRANULE_SIZE); redzone_end = (unsigned long)ptr + page_size(page); - kasan_unpoison_memory(ptr, size); + /* ksize() in __do_krealloc() already unpoisoned the memory. */ + if (!realloc) + kasan_unpoison_memory(ptr, size); kasan_poison_memory((void *)redzone_start, redzone_end - redzone_start, KASAN_PAGE_REDZONE); return (void *)ptr; } +void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size, + gfp_t flags) +{ + return ____kasan_kmalloc_large(virt_to_page(ptr), ptr, size, flags, false); +} + void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags) { struct page *page; @@ -419,7 +430,7 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag page = virt_to_head_page(object); if (unlikely(!PageSlab(page))) - return __kasan_kmalloc_large(object, size, flags); + return ____kasan_kmalloc_large(page, object, size, flags, true); else return ____kasan_kmalloc(page->slab_cache, object, size, flags, true); diff --git a/mm/slub.c b/mm/slub.c index 1d3f2355df3b..afb035b0bf2d 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3535,8 +3535,7 @@ static void early_kmem_cache_node_alloc(int node) init_object(kmem_cache_node, n, SLUB_RED_ACTIVE); init_tracking(kmem_cache_node, n); #endif - n = kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node), - GFP_KERNEL); + n = kasan_slab_alloc(kmem_cache_node, n, GFP_KERNEL); page->freelist = get_freepointer(kmem_cache_node, n); page->inuse = 1; page->frozen = 0; -- 2.29.0.rc1.297.gfa9743e501-goog
