Re: [PATCH v3 3/4] platform/x86: hp-bioscfg: Fix error handling in hp_add_other_attributes()

[Ilpo Järvinen]

On Mon, 13 Nov 2023, Harshit Mogalapalli wrote:

> 'attr_name_kobj' is allocated using kzalloc, but on all the error paths we
> don't free it, hence we have a memory leak. Fix it by adding kfree().

Don't use "we".

This is still somewhat confusing... I think it would be better with these 
two amendments.

Fix the error path before kobject_init_and_add() by adding kfree().

> kobject_put() must be always called after passing the object to
> kobject_init_and_add(). Only the error path which is immediately next
> to kobject_init_and_add() calls kobject_put() and not any other error
> path after it.
> 
> Fix the error handling by moving the kobject_put() into the goto label

Fix the error handling after kobject_init_and_add() by moving ...

> err_other_attr_init that is already used by all the error paths after
> kobject_init_and_add().
> 
> Fixes: a34fc329b189 ("platform/x86: hp-bioscfg: bioscfg")
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <error27@xxxxxxxxx>
> Closes: https://lore.kernel.org/r/202309201412.on0VXJGo-lkp@xxxxxxxxx/
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx>
> ---
> This is based on static analysis, only compile tested.
> 
> v2->v3: Improve commit message as suggested by Iplo on v2.
> https://lore.kernel.org/all/1b58df2d-b444-ddb7-7533-9911d35f8f7@xxxxxxxxxxxxxxx/
> ---
>  drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> index a3599498c4e8..6ddca857cc4d 100644
> --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> @@ -575,77 +575,79 @@ static void release_attributes_data(void)
>  /**
>   * hp_add_other_attributes() - Initialize HP custom attributes not
>   * reported by BIOS and required to support Secure Platform and Sure
>   * Start.
>   *
>   * @attr_type: Custom HP attribute not reported by BIOS
>   *
>   * Initialize all 2 types of attributes: Platform and Sure Start
>   * object.  Populates each attribute types respective properties
>   * under sysfs files.
>   *
>   * Returns zero(0) if successful. Otherwise, a negative value.
>   */
>  static int hp_add_other_attributes(int attr_type)
>  {
>  	struct kobject *attr_name_kobj;
>  	union acpi_object *obj = NULL;
>  	int ret;
>  	char *attr_name;
>  
>  	attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
>  	if (!attr_name_kobj)
>  		return -ENOMEM;
>  
>  	mutex_lock(&bioscfg_drv.mutex);
>  
>  	/* Check if attribute type is supported */
>  	switch (attr_type) {
>  	case HPWMI_SECURE_PLATFORM_TYPE:
>  		attr_name_kobj->kset = bioscfg_drv.authentication_dir_kset;
>  		attr_name = SPM_STR;
>  		break;
>  
>  	case HPWMI_SURE_START_TYPE:
>  		attr_name_kobj->kset = bioscfg_drv.main_dir_kset;
>  		attr_name = SURE_START_STR;
>  		break;
>  
>  	default:
>  		pr_err("Error: Unknown attr_type: %d\n", attr_type);
>  		ret = -EINVAL;
> -		goto err_other_attr_init;
> +		kfree(attr_name_kobj);
> +		goto unlock_drv_mutex;
>  	}
>  
>  	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;
>  	}
>  
>  	/* Populate attribute data */
>  	switch (attr_type) {
>  	case HPWMI_SECURE_PLATFORM_TYPE:
>  		ret = hp_populate_secure_platform_data(attr_name_kobj);
>  		break;
>  
>  	case HPWMI_SURE_START_TYPE:
>  		ret = hp_populate_sure_start_data(attr_name_kobj);
>  		break;
>  
>  	default:
>  		ret = -EINVAL;
>  	}
>  
>  	if (ret)
>  		goto err_other_attr_init;
>  
>  	mutex_unlock(&bioscfg_drv.mutex);
>  	return 0;
>  
>  err_other_attr_init:
> +	kobject_put(attr_name_kobj);
> +unlock_drv_mutex:
>  	mutex_unlock(&bioscfg_drv.mutex);
>  	kfree(obj);
>  	return ret;
>  }
>