Re: [PATCH] cxl/hdm: Avoid NULL deref when component registers are missing

[Dave Jiang <dave.jiang@intel.com>]

On 3/29/23 2:35 PM, Dan Williams wrote:
> The cxl_port driver attempts to support endpoint devices that do not
> advertise a component register block, but by inspection
> devm_cxl_setup_hdm() passes a NULL @crb to helper functions that should
> be skipped.
> 
> Return early and skip setting target_count since that is only relevant
> for switch decoders, not endpoint decoders.
> 
> Fixes: 757f6448b100 ("cxl/hdm: Fix double allocation of @cxlhdm")
> Tested-by: Dave Jiang <dave.jiang@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
>   drivers/cxl/core/hdm.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index 5293fe13fce3..cc123996b1a4 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -123,7 +123,7 @@ struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
>   	crb = ioremap(port->component_reg_phys, CXL_COMPONENT_REG_BLOCK_SIZE);
>   	if (!crb && info && info->mem_enabled) {
>   		cxlhdm->decoder_count = info->ranges;
> -		cxlhdm->target_count = info->ranges;
> +		return cxlhdm;
>   	} else if (!crb) {
>   		dev_err(dev, "No component registers mapped\n");
>   		return ERR_PTR(-ENXIO);
>