Subject: Re: [PATCH] vringh: Use wiov->used to check for read/write desc order

From: "Michael S. Tsirkin" <[email-masked]>
Date: Wed, 23 Jun 2021 16:09:52 -0400

On Tue, Jun 22, 2021 at 05:07:53PM +0530, Neeraj Upadhyay wrote:
> As iov->used is incremented when descriptors are processed
> in __vringh_iov(), use it to check for incorrect read
> and write descriptor order.

Could the commit log be clearer? why is wiov->i incorrect here?

> Signed-off-by: Neeraj Upadhyay <[email-masked]>
> ---
>  drivers/vhost/vringh.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
> index 4af8fa2..14e2043 100644
> --- a/drivers/vhost/vringh.c
> +++ b/drivers/vhost/vringh.c
> @@ -359,7 +359,7 @@ __vringh_iov(struct vringh *vrh, u16 i,
>  			iov = wiov;
>  		else {
>  			iov = riov;
> -			if (unlikely(wiov && wiov->i)) {
> +			if (unlikely(wiov && wiov->used)) {
>  				vringh_bad("Readable desc %p after writable",
>  					   &descs[i]);
>  				err = -EINVAL;
> -- 
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