Re: [PATCH] soc: microchip: mpfs-sys-controller: fix reference leak on failed device registration

[Conor Dooley]

On Thu, Apr 16, 2026 at 02:16:35AM +0800, Guangshuo Li wrote:
> When platform_device_register() fails in mpfs_sys_controller_probe(),
> the embedded struct device in subdevs[i] has already been initialized by
> device_initialize(), but the failure path only reports the error and
> does not drop the device reference for the current platform device:

Patch looks reasonable, but not urgent so I will pick it up after -rc1.
Looking around it doesn't look like this will be a unique patch, so for
other I would suggest that...

>   mpfs_sys_controller_probe()
>     -> platform_device_register(&subdevs[i])
>        -> device_initialize(&subdevs[i].dev)
>        -> setup_pdev_dma_masks(&subdevs[i])
>        -> platform_device_add(&subdevs[i])

...you redo this section, as it's not clear to me what this actually
is trying to communicate. AFAIU, what's wrong here is that
device_initialize() calls kobject_init(), which needs a kobject_put()
to clean up after it on failure. But this code snippet doesn't tell me
that, I had to go look for where the reference count was actually
incremented.

> 
> This leads to a reference leak when platform_device_register() fails.
> Fix this by calling platform_device_put() after reporting the error.
> 
> The issue was identified by a static analysis tool I developed and
> confirmed by manual review.
> 
> Fixes: d0054a470c339 ("soc: add microchip polarfire soc system controller")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
> ---
>  drivers/soc/microchip/mpfs-sys-controller.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/microchip/mpfs-sys-controller.c b/drivers/soc/microchip/mpfs-sys-controller.c
> index 10b2fc39da66..404c31daf459 100644
> --- a/drivers/soc/microchip/mpfs-sys-controller.c
> +++ b/drivers/soc/microchip/mpfs-sys-controller.c
> @@ -168,8 +168,10 @@ static int mpfs_sys_controller_probe(struct platform_device *pdev)
>  
>  	for (i = 0; i < ARRAY_SIZE(subdevs); i++) {
>  		subdevs[i].dev.parent = dev;
> -		if (platform_device_register(&subdevs[i]))
> +		if (platform_device_register(&subdevs[i])) {
>  			dev_warn(dev, "Error registering sub device %s\n", subdevs[i].name);
> +			platform_device_put(&subdevs[i]);
> +		}
>  	}
>  
>  	dev_info(&pdev->dev, "Registered MPFS system controller\n");
> -- 
> 2.43.0
>

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