Re: [PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE

[Michael S. Tsirkin]

On Fri, Feb 09, 2018 at 05:45:49PM +0800, 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
> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>

Acked-by: Michael S. Tsirkin <mst@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..6051a5f 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 * sizeof(void *) > KMALLOC_MAX_SIZE)
> +		return NULL;
>  	return kcalloc(size, sizeof(void *), gfp);
>  }
>  
> -- 
> 2.7.4