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authorFeng Tang <feng.tang@intel.com>2022-10-21 11:24:04 +0800
committerVlastimil Babka <vbabka@suse.cz>2022-11-10 16:27:46 +0100
commit5d1ba31087627423dfb2bd87badd62361701997b (patch)
tree30115b55a761164a8b64a1e1fdbdef8842ef8ada /mm/kasan
parent9ce67395f5a0cdec6ce152d26bfda13b98b25c01 (diff)
mm: kasan: Extend kasan_metadata_size() to also cover in-object size
When kasan is enabled for slab/slub, it may save kasan' free_meta data in the former part of slab object data area in slab object's free path, which works fine. There is ongoing effort to extend slub's debug function which will redzone the latter part of kmalloc object area, and when both of the debug are enabled, there is possible conflict, especially when the kmalloc object has small size, as caught by 0Day bot [1]. To solve it, slub code needs to know the in-object kasan's meta data size. Currently, there is existing kasan_metadata_size() which returns the kasan's metadata size inside slub's metadata area, so extend it to also cover the in-object meta size by adding a boolean flag 'in_object'. There is no functional change to existing code logic. [1]. https://lore.kernel.org/lkml/YuYm3dWwpZwH58Hu@xsang-OptiPlex-9020/ Reported-by: kernel test robot <oliver.sang@intel.com> Suggested-by: Andrey Konovalov <andreyknvl@gmail.com> Signed-off-by: Feng Tang <feng.tang@intel.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Diffstat (limited to 'mm/kasan')
-rw-r--r--mm/kasan/generic.c19
1 files changed, 13 insertions, 6 deletions
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index d8b5590f9484..b076f597a378 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -450,15 +450,22 @@ void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
__memset(alloc_meta, 0, sizeof(*alloc_meta));
}
-size_t kasan_metadata_size(struct kmem_cache *cache)
+size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object)
{
+ struct kasan_cache *info = &cache->kasan_info;
+
if (!kasan_requires_meta())
return 0;
- return (cache->kasan_info.alloc_meta_offset ?
- sizeof(struct kasan_alloc_meta) : 0) +
- ((cache->kasan_info.free_meta_offset &&
- cache->kasan_info.free_meta_offset != KASAN_NO_FREE_META) ?
- sizeof(struct kasan_free_meta) : 0);
+
+ if (in_object)
+ return (info->free_meta_offset ?
+ 0 : sizeof(struct kasan_free_meta));
+ else
+ return (info->alloc_meta_offset ?
+ sizeof(struct kasan_alloc_meta) : 0) +
+ ((info->free_meta_offset &&
+ info->free_meta_offset != KASAN_NO_FREE_META) ?
+ sizeof(struct kasan_free_meta) : 0);
}
static void __kasan_record_aux_stack(void *addr, bool can_alloc)