Re: [PATCH net] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE

[Jason Wang]

On 2018å02æ07æ 23:15, Michael S. Tsirkin wrote:
> On Wed, Feb 07, 2018 at 05:17:59PM +0800, Jason Wang wrote:
> > On 2018å02æ07æ 16:08, Jason Wang wrote:
> > > To avoid slab to warn about exceeded size, fail early if queue
> > > occupies more than KMALLOC_MAX_SIZE.
> > >
> > > Reported-by: syzbot+e4d4f9ddd4295539735d@xxxxxxxxxxxxxxxxxxxxxxxxx
> > > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> > > ---
> > >    include/linux/ptr_ring.h | 2 ++
> > >    1 file changed, 2 insertions(+)
> > >
> > > diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
> > > index 1883d61..4b862da 100644
> > > --- a/include/linux/ptr_ring.h
> > > +++ b/include/linux/ptr_ring.h
> > > @@ -466,6 +466,8 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
> > >    static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
> > >    {
> > > +	if (size > KMALLOC_MAX_SIZE)
> > > +		return NULL;
> > >    	return kcalloc(size, sizeof(void *), gfp);
> > >    }
> > Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
> That's probably not enough. How about switching to kvmalloc and limiting
> this drastically to e.g. 64K. I vaguely remember that some wise man said
> that should be enough for everybody :)

Okay, let me post a V2 to see if there's any objection.

Thanks