linux-kernel - Re: [PATCH] timekeeping: Fix resource leak in tk_aux_sysfs

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Message-ID: <87ldk8bgno.ffs@tglx>
Date: Fri, 14 Nov 2025 19:41:47 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Malaya Kumar Rout <mrout@...hat.com>, linux-kernel@...r.kernel.org
Cc: mrout@...hat.com, lyude@...hat.com, malayarout91@...il.com, John Stultz
 <jstultz@...gle.com>, Stephen Boyd <sboyd@...nel.org>
Subject: Re: [PATCH] timekeeping: Fix resource leak in tk_aux_sysfs_init()
 error paths

On Mon, Nov 10 2025 at 12:30, Malaya Kumar Rout wrote:
> @@ -3060,29 +3060,37 @@ static const struct attribute_group aux_clock_enable_attr_group = {
>  static int __init tk_aux_sysfs_init(void)
>  {
>  	struct kobject *auxo, *tko = kobject_create_and_add("time", kernel_kobj);
> +	int ret;
>  
>  	if (!tko)
>  		return -ENOMEM;
>  
>  	auxo = kobject_create_and_add("aux_clocks", tko);
>  	if (!auxo) {
> -		kobject_put(tko);
> -		return -ENOMEM;
> +		ret = -ENOMEM;
> +		goto err_put_tko;

This ret variable is completely pointless as it is set to -ENOMEM in
every error path. Just make the error path do 'return -ENOMEM;', no?

>  	}
>  
>  	for (int i = 0; i < MAX_AUX_CLOCKS; i++) {
>  		char id[2] = { [0] = '0' + i, };
>  		struct kobject *clk = kobject_create_and_add(id, auxo);
>  
> -		if (!clk)
> -			return -ENOMEM;
> -
> -		int ret = sysfs_create_group(clk, &aux_clock_enable_attr_group);
> +		if (!clk) {
> +			ret = -ENOMEM;
> +			goto err_put_auxo;
> +		}
>  
> +		ret = sysfs_create_group(clk, &aux_clock_enable_attr_group);
>  		if (ret)
> -			return ret;
> +			goto err_put_auxo;
>  	}
>  	return 0;
> +
> +err_put_auxo:
> +	kobject_put(auxo);
> +err_put_tko:
> +	kobject_put(tko);
> +	return ret;

You can simplify that with _one_ error label:

err:
	kobject_put(auxo);
	kobject_put(tko);
	return -ENOMEM;
        
because kobject_put() is NULL pointer safe.

Thanks,

        tglx