On Sun, Sep 11, 2022 at 5:57 AM Feng Tang <feng.tang@xxxxxxxxx> wrote: > > Hi Andrey, > > Thanks for reviewing this series! > > On Sun, Sep 11, 2022 at 07:14:55AM +0800, Andrey Konovalov wrote: > > On Wed, Sep 7, 2022 at 9:11 AM Feng Tang <feng.tang@xxxxxxxxx> wrote: > > > > > > 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 > > > 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] > > > > > > For better information for slab/slub, add free_meta's data size > > > into 'struct kasan_cache', so that its users can take right action > > > to avoid data conflict. > > > > > > [1]. https://lore.kernel.org/lkml/YuYm3dWwpZwH58Hu@xsang-OptiPlex-9020/ > > > Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> > > > Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx> > > > Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > > > --- > > > include/linux/kasan.h | 2 ++ > > > mm/kasan/common.c | 2 ++ > > > 2 files changed, 4 insertions(+) > > > > > > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > > > index b092277bf48d..293bdaa0ba09 100644 > > > --- a/include/linux/kasan.h > > > +++ b/include/linux/kasan.h > > > @@ -100,6 +100,8 @@ static inline bool kasan_has_integrated_init(void) > > > struct kasan_cache { > > > int alloc_meta_offset; > > > int free_meta_offset; > > > + /* size of free_meta data saved in object's data area */ > > > + int free_meta_size_in_object; > > > > I thinks calling this field free_meta_size is clear enough. Thanks! > > Yes, the name does look long. The "in_object" was added to make it > also a flag for whether the free meta is saved inside object's data > area. > > For 'free_meta_size', the code logic in slub should be: > > if (info->free_meta_offset == 0 && > info->free_meta_size >= ...) I'd say you can keep the current logic and just rename the field to make it shorter. But up to you, I'm fine with either approach. Thanks!
