Re: [PATCH for-next v4 2/4] io_uring: introduce fixed buffer support for io_uring_cmd

[Jens Axboe <axboe@kernel.dk>]

On 9/5/22 7:48 AM, Kanchan Joshi wrote:
> @@ -76,8 +77,21 @@ int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  {
>  	struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
>  
> -	if (sqe->rw_flags || sqe->__pad1)
> +	if (sqe->__pad1)
>  		return -EINVAL;
> +
> +	ioucmd->flags = READ_ONCE(sqe->uring_cmd_flags);
> +	req->buf_index = READ_ONCE(sqe->buf_index);
> +	if (ioucmd->flags & IORING_URING_CMD_FIXED) {
> +		struct io_ring_ctx *ctx = req->ctx;
> +		u16 index;
> +
> +		if (unlikely(req->buf_index >= ctx->nr_user_bufs))
> +			return -EFAULT;
> +		index = array_index_nospec(req->buf_index, ctx->nr_user_bufs);
> +		req->imu = ctx->user_bufs[index];
> +		io_req_set_rsrc_node(req, ctx, 0);
> +	}

Should that buf_index read and assignment be inside the
IORING_URING_CMD_FIXED section?

-- 
Jens Axboe