On 07/28/2016 06:31 PM, Alexander Potapenko wrote: > When free_meta_offset is not zero, it is usually aligned on 4 bytes, > because the size of preceding kasan_alloc_meta is aligned on 4 bytes. > As a result, accesses to kasan_free_meta fields may be misaligned. > > Signed-off-by: Alexander Potapenko <[email protected]> > --- > mm/kasan/kasan.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c > index 6845f92..0379551 100644 > --- a/mm/kasan/kasan.c > +++ b/mm/kasan/kasan.c > @@ -390,7 +390,8 @@ void kasan_cache_create(struct kmem_cache *cache, size_t > *size, > /* Add free meta. */ > if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor || > cache->object_size < sizeof(struct kasan_free_meta)) { > - cache->kasan_info.free_meta_offset = *size; > + cache->kasan_info.free_meta_offset = > + ALIGN(*size, sizeof(void *));
This cannot work. I slightly changed metadata layout in http://lkml.kernel.org/g/<[email protected]> which should also fix UBSAN's complain. > *size += sizeof(struct kasan_free_meta); > } > redzone_adjust = optimal_redzone(cache->object_size) - >
