On Sun, Feb 11, 2018 at 11:28:12AM +0800, Jason Wang wrote:
> Switch to use dividing to prevent integer overflow when size is too
> big to calculate allocation size properly.
>
> Reported-by: Eric Biggers <ebigge...@gmail.com>
> Fixes: 6e6e41c31122 ("ptr_ring: fail early if queue occupies more than
> KMALLOC_MAX_SIZE")
> Signed-off-by: Jason Wang <jasow...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> include/linux/ptr_ring.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
> index b884b77..e633522 100644
> --- a/include/linux/ptr_ring.h
> +++ b/include/linux/ptr_ring.h
> @@ -469,7 +469,7 @@ 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)
> + if (size > KMALLOC_MAX_SIZE / sizeof(void *))
> return NULL;
> return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
> }
> --
> 2.7.4
