> > static __always_inline void *
> > -slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
> > +slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, size_t orig_size,
> > unsigned long caller)
> > {
>
> The size of the object is available via a field in kmem_cache. And a
> pointer to the current kmem_cache is already passed to the function. Why
> is there a need to add an additional parameter?
That's because we want to do our best detecting bugs on
kmalloc-allocated objects.
kmalloc is using size classes, so e.g. when allocating 272 bytes the
object will be padded to 512.
As a result, placing that object at the end of the page won't really
help to detect out-of-bound accesses that are off by less than 270
bytes.
We probably need to better clarify this in the patch description.
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
