Re: [PATCHv6] dmaengine: fsl_raid: check fsl_re_chan_probe() return value

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] dmaengine: fsl_raid: decoupling total_chans from ridx leaks channels on remove
- [Medium] dmaengine: fsl_raid: unconditionally incrementing ridx for incompatible nodes exhausts slots
--

commit 698d683c6c412a8530d330dc178b5712397be8bf
Author: Rosen Penev <rosenp@gmail.com>

dmaengine: fsl_raid: check fsl_re_chan_probe() return value
    
This commit modifies fsl_re_probe to check the return value of
fsl_re_chan_probe and only increment total_chans on success. It also adds
NULL checks during channel removal in fsl_re_remove to prevent dereferencing
uninitialized slots.

> diff --git a/drivers/dma/fsl_raid.c b/drivers/dma/fsl_raid.c
> index 2d86f61105e52..83856d554b12b 100644
> --- a/drivers/dma/fsl_raid.c
> +++ b/drivers/dma/fsl_raid.c
> @@ -828,18 +828,30 @@ static int fsl_re_probe(struct platform_device *ofdev)
>  		}
>  		/* Find out the Job Rings present under each JQ */
>  		for_each_child_of_node(np, child) {
> -			rc = of_device_is_compatible(child,
> -					     "fsl,raideng-v1.0-job-ring");
> +			if (ridx >= FSL_RE_MAX_CHANS) {
> +				dev_warn(dev, "too many job rings, max %d\n", FSL_RE_MAX_CHANS);
> +				of_node_put(child);
> +				break;
> +			}
> +
> +			rc = of_device_is_compatible(child, "fsl,raideng-v1.0-job-ring");
> +			if (!rc) {
> +				ridx++;
> +				continue;
> +			}

[Severity: Medium]
When iterating child nodes, if a node is not compatible, does this code
incorrectly increment ridx?

This could waste limited job ring capacity (FSL_RE_MAX_CHANS) by advancing the
internal logical index for child nodes that are not job rings.

> +
> +			rc = fsl_re_chan_probe(ofdev, child, ridx, off);
>  			if (rc) {
> -				fsl_re_chan_probe(ofdev, child, ridx++, off);
> -				re_priv->total_chans++;
> +				dev_err(dev, "job ring %d probe failed: %d\n", ridx, rc);
> +				ridx++;
> +				continue;
>  			}
> +			ridx++;
> +			re_priv->total_chans++;

[Severity: High]
If any child node fails to probe or is skipped as incompatible, ridx is
incremented but total_chans is not. Does this create a persistent mismatch
between the array index and the channel count?

A subsequent successful probe would store the channel in re_priv->re_jrs at
an index greater than or equal to total_chans.

[ ... ]
> @@ -864,7 +876,8 @@ static void fsl_re_remove(struct platform_device *ofdev)
>  
>  	/* Cleanup chan related memory areas */
>  	for (i = 0; i < re_priv->total_chans; i++)
> -		fsl_re_remove_chan(re_priv->re_jrs[i]);
> +		if (re_priv->re_jrs[i])
> +			fsl_re_remove_chan(re_priv->re_jrs[i]);

[Severity: High]
Does this cleanup loop miss successfully populated channels stored at indices
greater than or equal to total_chans?

Since total_chans is used as the exclusive upper bound, successfully probed
channels placed at higher indices (due to previous skipped or failed nodes)
could be bypassed and leaked during device removal.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260916230228.283615-1-rosenp@gmail.com?part=1