linux-kernel - Re: [PATCH] of: unittest: Fix device reference count leak in of_unittest_pci_node

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Message-ID: <20250922202014.GA1254345-robh@kernel.org>
Date: Mon, 22 Sep 2025 15:20:14 -0500
From: Rob Herring <robh@...nel.org>
To: Ma Ke <make24@...as.ac.cn>
Cc: saravanak@...gle.com, lizhi.hou@....com, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] of: unittest: Fix device reference count leak in
 of_unittest_pci_node_verify

On Sat, Sep 20, 2025 at 04:51:35PM +0800, Ma Ke wrote:
> In of_unittest_pci_node_verify(), when the add parameter is false,
> device_find_any_child() obtains a reference to a child device. This
> function implicitly calls get_device() to increment the device's
> reference count before returning the pointer. However, the caller
> fails to properly release this reference by calling put_device(),
> leading to a device reference count leak.
> 
> As the comment of device_find_any_child states: "NOTE: you will need
> to drop the reference with put_device() after use".
> 
> Cc: stable@...r.kernel.org
> Fixes: 26409dd04589 ("of: unittest: Add pci_dt_testdrv pci driver")
> Signed-off-by: Ma Ke <make24@...as.ac.cn>
> ---
>  drivers/of/unittest.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
> index e3503ec20f6c..d225e73781fe 100644
> --- a/drivers/of/unittest.c
> +++ b/drivers/of/unittest.c
> @@ -4271,7 +4271,7 @@ static struct platform_driver unittest_pci_driver = {
>  static int of_unittest_pci_node_verify(struct pci_dev *pdev, bool add)
>  {
>  	struct device_node *pnp, *np = NULL;
> -	struct device *child_dev;
> +	struct device *child_dev = NULL;
>  	char *path = NULL;
>  	const __be32 *reg;
>  	int rc = 0;
> @@ -4306,6 +4306,8 @@ static int of_unittest_pci_node_verify(struct pci_dev *pdev, bool add)
>  	kfree(path);
>  	if (np)
>  		of_node_put(np);
> +	if (child_dev)
> +		put_device(child_dev);

This can go in the else clause. Then child_dev doesn't need to be 
initialized to NULL.

>  
>  	return rc;
>  }
> -- 
> 2.17.1
>