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

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Message-ID: <20241119215042.0000617b@nvidia.com>
Date: Tue, 19 Nov 2024 21:50:42 +0200
From: Zhi Wang <zhiw@...dia.com>
To: <alejandro.lucero-palau@....com>
CC: <linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
	<dan.j.williams@...el.com>, <martin.habets@...inx.com>,
	<edward.cree@....com>, <davem@...emloft.net>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <edumazet@...gle.com>, Alejandro Lucero
	<alucerop@....com>
Subject: Re: [PATCH v5 10/27] cxl: harden resource_contains checks to handle
 zero size resources

On Mon, 18 Nov 2024 16:44:17 +0000
<alejandro.lucero-palau@....com> wrote:

> From: Alejandro Lucero <alucerop@....com>
> 
> 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 <alucerop@....com>
> ---
>  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);