linux-kernel - Re: [PATCH v3 2/2] platform/x86: hp-bioscfg: Fix reference leak

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Message-ID: <eaabc245-bf5a-b4a0-f319-1e1c4f02d7a@linux.intel.com>
Date:   Mon, 25 Sep 2023 16:38:30 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Armin Wolf <W_Armin@....de>
cc:     markpearson@...ovo.com, jorge.lopez2@...com,
        Hans de Goede <hdegoede@...hat.com>, markgross@...nel.org,
        platform-driver-x86@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] platform/x86: hp-bioscfg: Fix reference leak

On Mon, 25 Sep 2023, Armin Wolf wrote:

> If a duplicate attribute is found using kset_find_obj(), a reference
> to that attribute is returned which needs to be disposed accordingly
> using kobject_put(). Use kobject_put() to dispose the duplicate
> attribute in such a case.
> As a side note, a very similar bug was fixed in
> commit 7295a996fdab ("platform/x86: dell-sysman: Fix reference leak"),
> so it seems that the bug was copied from that driver.
> 
> Compile-tested only.
> 
> Fixes: a34fc329b189 ("platform/x86: hp-bioscfg: bioscfg")
> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Signed-off-by: Armin Wolf <W_Armin@....de>
> ---
> Changes in v3:
> - no changes
> Changes in v2:
> - add patch
> ---
>  drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> index 8c4f9e12f018..0c83e66f8d0b 100644
> --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> @@ -659,7 +659,7 @@ static int hp_init_bios_package_attribute(enum hp_wmi_data_type attr_type,
>  					  const char *guid, int min_elements,
>  					  int instance_id)
>  {
> -	struct kobject *attr_name_kobj;
> +	struct kobject *attr_name_kobj, *duplicate;
>  	union acpi_object *elements;
>  	struct kset *temp_kset;
> 
> @@ -704,8 +704,11 @@ static int hp_init_bios_package_attribute(enum hp_wmi_data_type attr_type,
>  	}
> 
>  	/* All duplicate attributes found are ignored */
> -	if (kset_find_obj(temp_kset, str_value)) {
> +	duplicate = kset_find_obj(temp_kset, str_value);
> +	if (duplicate) {
>  		pr_debug("Duplicate attribute name found - %s\n", str_value);
> +		/* kset_find_obj() returns a reference */
> +		kobject_put(duplicate);
>  		goto pack_attr_exit;
>  	}
> 
> @@ -768,7 +771,7 @@ static int hp_init_bios_buffer_attribute(enum hp_wmi_data_type attr_type,
>  					 const char *guid, int min_elements,
>  					 int instance_id)
>  {
> -	struct kobject *attr_name_kobj;
> +	struct kobject *attr_name_kobj, *duplicate;
>  	struct kset *temp_kset;
>  	char str[MAX_BUFF_SIZE];
> 
> @@ -794,8 +797,11 @@ static int hp_init_bios_buffer_attribute(enum hp_wmi_data_type attr_type,
>  		temp_kset = bioscfg_drv.main_dir_kset;
> 
>  	/* All duplicate attributes found are ignored */
> -	if (kset_find_obj(temp_kset, str)) {
> +	duplicate = kset_find_obj(temp_kset, str);
> +	if (duplicate) {
>  		pr_debug("Duplicate attribute name found - %s\n", str);
> +		/*kset_find_obj() returns a reference */

Thanks. Whitespace is missing here.

Other than that, 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

> +		kobject_put(duplicate);
>  		goto buff_attr_exit;
>  	}
> 
> --
> 2.39.2
> 

-- 
 i.