On Tue, Feb 27, 2007 at 09:14:25PM +0300, Evgeniy Polyakov ([EMAIL PROTECTED])
wrote:
> On Tue, Feb 27, 2007 at 10:00:52AM -0800, David Miller ([EMAIL PROTECTED])
> wrote:
> > It's unfortunately an easy mistake to make since kfree() accepts any
> > pointer type without warning.
> >
> > What would be really nice is if someone could come up with a way for
> > kfree() to disallow being passed objects that are meant to be released
> > via some other mechanism. So that, for example:
> >
> > kfree(skb);
> >
> > would warn or fail to compile, but the kfree_skb() code could go:
> >
> > kmem_cache_free_I_KNOW_WHAT_I_AM_DOING(skbuff_head_cache, skb);
> >
> > :-)
>
> Something like that? (not tested, will do if starting point looks
> correct - it checks if requested to be freed size is equal to one of the
> kmalloc() size, and warns if kmalloc cache is not that one where
> we are going to free an object):
>
> diff --git a/mm/slab.c b/mm/slab.c
> index c610062..bcb29df 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -3757,6 +3757,15 @@ void kfree(const void *objp)
> local_irq_save(flags);
> kfree_debugcheck(objp);
> c = virt_to_cache(objp);
> +
> + {
> + int size = kmem_cache_size(c);
> + struct cache_sizes *csizep = malloc_sizes;
> + while (size != csizep->cs_size)
that needs a check for csizep != NULL too obviously.
Proof of concept, what do you expect? :)
> + csizep++;
> + WARN_ON(csizep != c);
> + }
> +
> debug_check_no_locks_freed(objp, obj_size(c));
> __cache_free(c, (void *)objp);
> local_irq_restore(flags);
>
> --
> Evgeniy Polyakov
> -
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--
Evgeniy Polyakov
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