From: Evgeniy Polyakov <[EMAIL PROTECTED]>
Date: Tue, 27 Feb 2007 21:20:01 +0300
> 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? :)
It's a great run-time check, for sure, and definitely something
that we should add when SLAB_DEBUG is enabled.
A compile-time check would be "really neat" :-)
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
