Re: [PATCH] platform/x86: hp-bioscfg: Fix error handling in hp_add_other_attributes()

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Fri, 10 Nov 2023, Harshit Mogalapalli wrote:

> 1. acpi_object *obj is unused in this function, so delete it, also
>    delete a unnecessary kfree(obj);
> 2. Fix a memory leak of 'attr_name_kobj' in the error handling path.
> 3. When kobject_init_and_add() fails on every subsequent error path call
>    kobject_put() to cleanup.
> 
> Fixes: a34fc329b189 ("platform/x86: hp-bioscfg: bioscfg")
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <error27@gmail.com>
> Closes: https://lore.kernel.org/r/202309201412.on0VXJGo-lkp@intel.com/
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
> ---
> This is only compile tested, based on static analysis.
> ---
>  drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> index 5798b49ddaba..b28e52b64690 100644
> --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> @@ -588,7 +588,6 @@ static void release_attributes_data(void)
>  static int hp_add_other_attributes(int attr_type)
>  {
>  	struct kobject *attr_name_kobj;
> -	union acpi_object *obj = NULL;
>  	int ret;
>  	char *attr_name;
>  
> @@ -596,8 +595,8 @@ static int hp_add_other_attributes(int attr_type)
>  
>  	attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
>  	if (!attr_name_kobj) {
> -		ret = -ENOMEM;
> -		goto err_other_attr_init;
> +		mutex_unlock(&bioscfg_drv.mutex);

I don't understand why this has to be inside the mutex at all, cannot 
you just move it outside of the mutex and then there's no need to unlock?

> +		return -ENOMEM;
>  	}
>  
>  	/* Check if attribute type is supported */
> @@ -614,15 +613,15 @@ static int hp_add_other_attributes(int attr_type)
>  
>  	default:
>  		pr_err("Error: Unknown attr_type: %d\n", attr_type);
> -		ret = -EINVAL;
> -		goto err_other_attr_init;
> +		kfree(attr_name_kobj);
> +		mutex_unlock(&bioscfg_drv.mutex);
> +		return -EINVAL;

Add a new label for unlock and goto to it instead.

>  	}
>  
>  	ret = kobject_init_and_add(attr_name_kobj, &attr_name_ktype,
>  				   NULL, "%s", attr_name);
>  	if (ret) {
>  		pr_err("Error encountered [%d]\n", ret);
> -		kobject_put(attr_name_kobj);
>  		goto err_other_attr_init;
>  	}
>  
> @@ -647,10 +646,9 @@ static int hp_add_other_attributes(int attr_type)
>  
>  	mutex_unlock(&bioscfg_drv.mutex);
>  	return 0;
> -
>  err_other_attr_init:
> +	kobject_put(attr_name_kobj);

unlock:

>  	mutex_unlock(&bioscfg_drv.mutex);
> -	kfree(obj);
>  	return ret;
>  }
>  
> 


-- 
 i.