Re: [PATCH v4 6/6] cxl/region: Reject poison scan for decoder without a partition

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Returning `-ENODEV` for an unmapped partition aborts the entire poison collection iteration.
--

--- Patch [6]: [PATCH v4 6/6] cxl/region: Reject poison scan for decoder without a partition ---
commit 8cb40391df3fd49e0cd36f0f034423d0470da73b
Author: Richard Cheng <[email protected]>

cxl/region: Reject poison scan for decoder without a partition

__cxl_dpa_reserve() may leave cxled->part at -1 when a decoder's DPA
range doesn't map to any reported partition, while still keeping
dpa_res. This commit returns -ENODEV before accessing the partition array
when no partition was assigned to avoid an out-of-bounds read.

> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index b7dc5d4988da7..afe3fb57b7fe2 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -2954,6 +2954,8 @@ static int poison_by_decoder(struct device *dev, void *arg)
>  	cxled = to_cxl_endpoint_decoder(dev);
>  	if (!cxled->dpa_res)
>  		return rc;
> +	if (cxled->part < 0)
> +		return -ENODEV;

[Severity: Medium]
Since poison_by_decoder() is used as an iterator callback for
device_for_each_child(), does returning -ENODEV here prematurely abort the
entire poison collection iteration?

If any decoder on the port has an unmapped partition, returning a negative
error code would halt the traversal. The sysfs trigger would then fail with
-ENODEV, skipping poison collection for all subsequent decoders.

Would it be better to return 0 here to just skip the unmapped decoder and
continue iterating over the remaining ones?

>  
>  	cxlmd = cxled_to_memdev(cxled);
>  	cxlds = cxlmd->cxlds;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=6