Re: [PATCH 1/6] Convert virtio_console to struct_size

[Kees Cook]

On Thu, Jun 7, 2018 at 7:57 AM, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
>
> Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> ---
>  drivers/char/virtio_console.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 21085515814f..4bf7c06c2343 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -433,8 +433,7 @@ static struct port_buffer *alloc_buf(struct virtio_device *vdev, size_t buf_size
>          * Allocate buffer and the sg list. The sg list array is allocated
>          * directly after the port_buffer struct.
>          */
> -       buf = kmalloc(sizeof(*buf) + sizeof(struct scatterlist) * pages,
> -                     GFP_KERNEL);
> +       buf = kmalloc(struct_size(buf, sg, pages), GFP_KERNEL);
>         if (!buf)
>                 goto fail;

I feel like this one should have been caught by Coccinelle... maybe
the transitive case got missed? Regardless, I'll figure out how to
improve the script and/or take these.

Thanks!

-Kees

-- 
Kees Cook
Pixel Security