Subject: Re: [PATCH v5 10/27] cxl: harden resource_contains checks to handle zero size resources

From: Zhi Wang <[email-masked]>
Date: Tue, 19 Nov 2024 21:50:42 +0200

On Mon, 18 Nov 2024 16:44:17 +0000
<[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.
> 

Does this trigger a bug? Looks like this should be with a Fixes: tag?

Z.

> Signed-off-by: Alejandro Lucero <[email-masked]>
> ---
>  drivers/cxl/core/hdm.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index 223c273c0cd1..c58d6b8f9b58 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -327,10 +327,13 @@ 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)) {
>  		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)) {
>  		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);