linux-kernel - Re: [PATCH 08/26] virtio-mem: use array

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Message-ID: <20230626065202-mutt-send-email-mst@kernel.org>
Date:   Mon, 26 Jun 2023 06:59:09 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Julia Lawall <Julia.Lawall@...ia.fr>
Cc:     David Hildenbrand <david@...hat.com>, keescook@...omium.org,
        kernel-janitors@...r.kernel.org, Jason Wang <jasowang@...hat.com>,
        Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/26] virtio-mem: use array_size

On Fri, Jun 23, 2023 at 11:14:39PM +0200, Julia Lawall wrote:
> Use array_size to protect against multiplication overflows.
> 
> The changes were done using the following Coccinelle semantic patch:
> 
> // <smpl>
> @@
>     expression E1, E2;
>     constant C1, C2;
>     identifier alloc = {vmalloc,vzalloc};
> @@
>     
> (
>       alloc(C1 * C2,...)
> |
>       alloc(
> -           (E1) * (E2)
> +           array_size(E1, E2)
>       ,...)
> )
> // </smpl>
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@...ia.fr>
> 
> ---
>  drivers/virtio/virtio_mem.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

can't hurt I guess.

Acked-by: Michael S. Tsirkin <mst@...hat.com>


> diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
> index 835f6cc2fb66..a4dfe7aab288 100644
> --- a/drivers/virtio/virtio_mem.c
> +++ b/drivers/virtio/virtio_mem.c
> @@ -399,7 +399,7 @@ static int virtio_mem_bbm_bb_states_prepare_next_bb(struct virtio_mem *vm)
>  	if (vm->bbm.bb_states && old_pages == new_pages)
>  		return 0;
>  
> -	new_array = vzalloc(new_pages * PAGE_SIZE);
> +	new_array = vzalloc(array_size(new_pages, PAGE_SIZE));
>  	if (!new_array)
>  		return -ENOMEM;
>
> @@ -465,7 +465,7 @@ static int virtio_mem_sbm_mb_states_prepare_next_mb(struct virtio_mem *vm)
>  	if (vm->sbm.mb_states && old_pages == new_pages)
>  		return 0;
>  
> -	new_array = vzalloc(new_pages * PAGE_SIZE);
> +	new_array = vzalloc(array_size(new_pages, PAGE_SIZE));
>  	if (!new_array)
>  		return -ENOMEM;
>  
> @@ -588,7 +588,7 @@ static int virtio_mem_sbm_sb_states_prepare_next_mb(struct virtio_mem *vm)
>  	if (vm->sbm.sb_states && old_pages == new_pages)
>  		return 0;
>  
> -	new_bitmap = vzalloc(new_pages * PAGE_SIZE);
> +	new_bitmap = vzalloc(array_size(new_pages, PAGE_SIZE));
>  	if (!new_bitmap)
>  		return -ENOMEM;
>