Re: [PATCH v2 4/4] 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:

This changelog needs to be rewritten, it contains multiple errors. I 
suppose even this patch could be split into two but I'll not be too picky 
here if you insist on fixing them in the same patch.

> We have two issues:
> 1. Memory leak of 'attr_name_kobj' in the error handling path.

True, but not specific enough to be useful.

> 2. When kobject_init_and_add() fails on every subsequent error path call
>    kobject_put() to cleanup.

This makes no sense. The only case when there old code had no issue is 
"when kobject_init_and_add() fails" but now your wording claims it to be 
source of problem. Please rephrase this.

> Both of these issues will be fixed when we add kobject_put() in the goto
> label, as kfree() is already part of kobject_put().

No, you're fixing a problem in the patch which is not covered by moving 
kobject_put()!

-- 
 i.

> 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>
> ---
> Only compile tested, based on static analysis
> v1-> v2: Split this into mutliple patches doing one thing in a patch.
> ---
>  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 351d782f3e96..8c9f4f3227fc 100644
> --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> @@ -575,75 +575,77 @@ 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;
>  	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);
>  	return ret;
>  }
>