Subject: Re: [PATCH v3 07/20] cxl: harden resource_contains checks to handle zero size resources

From: Jonathan Cameron <[email-masked]>
Date: Fri, 13 Sep 2024 18:36:21 +0100

On Sat, 7 Sep 2024 09:18:23 +0100
<[email-masked]> wrote:

> From: Alejandro Lucero <[email-masked]>
> 
> For a resource defined with size zero, resource_contains returns
> always true.
> 
> Add resource size check before using it.
> 
> Signed-off-by: Alejandro Lucero <[email-masked]>
> ---
>  drivers/cxl/core/hdm.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index 3df10517a327..953a5f86a43f 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -327,10 +327,11 @@ static int __cxl_dpa_reserve(struct cxl_endpoint_decoder *cxled,
>  	cxled->dpa_res = res;
>  	cxled->skip = skipped;
>  
> -	if (resource_contains(&cxlds->pmem_res, res))
> +	if ((resource_size(&cxlds->pmem_res)) && (resource_contains(&cxlds->pmem_res, res))) {

Excess brackets + I'd break that over two lines.

>  		cxled->mode = CXL_DECODER_PMEM;
> -	else if (resource_contains(&cxlds->ram_res, res))
> +	} else if ((resource_size(&cxlds->ram_res)) && (resource_contains(&cxlds->ram_res, res))) {
Same here,

>  		cxled->mode = CXL_DECODER_RAM;
> +	}
>  	else {
>  		dev_warn(dev, "decoder%d.%d: %pr mixed mode not supported\n",
>  			 port->id, cxled->cxld.id, cxled->dpa_res);