| Message ID | 20241016154152.1376492-2-feng.tang@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/slub: Improve data handling of krealloc() when orig_size is enabled | expand |
On Thu, Oct 17, 2024 at 12:42 AM Feng Tang <feng.tang@intel.com> wrote: > > When 'orig_size' of kmalloc object is enabled by debug option, it > should either contains the actual requested size or the cache's > 'object_size'. > > But it's not true if that object is a kfence-allocated one, and the > data at 'orig_size' offset of metadata could be zero or other values. > This is not a big issue for current 'orig_size' usage, as init_object() > and check_object() during alloc/free process will be skipped for kfence > addresses. But it could cause trouble for other usage in future. > > Use the existing kfence helper kfence_ksize() which can return the > real original request size. > > Signed-off-by: Feng Tang <feng.tang@intel.com> > --- Looks good to me, Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > mm/slub.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/slub.c b/mm/slub.c > index af9a80071fe0..1d348899f7a3 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -768,6 +768,9 @@ static inline unsigned int get_orig_size(struct kmem_cache *s, void *object) > { > void *p = kasan_reset_tag(object); > > + if (is_kfence_address(object)) > + return kfence_ksize(object); > + > if (!slub_debug_orig_size(s)) > return s->object_size; > > -- > 2.27.0 >
diff --git a/mm/slub.c b/mm/slub.c index af9a80071fe0..1d348899f7a3 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -768,6 +768,9 @@ static inline unsigned int get_orig_size(struct kmem_cache *s, void *object) { void *p = kasan_reset_tag(object); + if (is_kfence_address(object)) + return kfence_ksize(object); + if (!slub_debug_orig_size(s)) return s->object_size;
When 'orig_size' of kmalloc object is enabled by debug option, it should either contains the actual requested size or the cache's 'object_size'. But it's not true if that object is a kfence-allocated one, and the data at 'orig_size' offset of metadata could be zero or other values. This is not a big issue for current 'orig_size' usage, as init_object() and check_object() during alloc/free process will be skipped for kfence addresses. But it could cause trouble for other usage in future. Use the existing kfence helper kfence_ksize() which can return the real original request size. Signed-off-by: Feng Tang <feng.tang@intel.com> --- mm/slub.c | 3 +++ 1 file changed, 3 insertions(+)