Re: [PATCH V3 5/9] iommufd: IOMMU_IOAS_MAP_FILE

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Oct 04, 2024 at 11:48:16AM -0700, Steve Sistare wrote:
>  
> +int iommufd_ioas_map_file(struct iommufd_ucmd *ucmd)
> +{
> +	struct iommu_ioas_map_file *cmd = ucmd->cmd;
> +	unsigned long iova = cmd->iova;
> +	struct iommufd_ioas *ioas;
> +	unsigned int flags = 0;
> +	int rc;
> +	struct file *file;
> +	unsigned long end;
> +
> +	if (cmd->iova >= ULONG_MAX || cmd->length >= ULONG_MAX)
> +		return -EOVERFLOW;
> +
> +	if (cmd->length > 0 &&
> +	    check_add_overflow(cmd->start, cmd->length - 1, &end))
> +		return -EOVERFLOW;

Why is this here? iopt_alloc_pages() does this validation and I don't
see math on these values between here and there?

Jason