linux-kernel - Re: [PATCH] platform/x86: think-lmi: Fix reference leak

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Message-ID: <7e68e66f-40a2-1ac7-416b-bf63bafa6fe7@linux.intel.com>
Date:   Mon, 25 Sep 2023 15:00:10 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Armin Wolf <W_Armin@....de>
cc:     markpearson@...ovo.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] platform/x86: think-lmi: Fix reference leak

On Sat, 23 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(). Move the setting name validation into a separate
> function to allow for this change without having to duplicate the
> cleanup code for this setting.
> 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: 1bcad8e510b2 ("platform/x86: think-lmi: Fix issues with duplicate attributes")
> Signed-off-by: Armin Wolf <W_Armin@....de>
> ---
>  drivers/platform/x86/think-lmi.c | 24 ++++++++++++++++++++----
>  1 file changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
> index 4be6f28d4600..3a396b763c49 100644
> --- a/drivers/platform/x86/think-lmi.c
> +++ b/drivers/platform/x86/think-lmi.c
> @@ -1344,6 +1344,24 @@ static void tlmi_release_attr(void)
>  	kset_unregister(tlmi_priv.authentication_kset);
>  }
> 
> +static int tlmi_validate_setting_name(struct kset *attribute_kset, char *name)
> +{
> +	struct kobject *duplicate;
> +
> +	if (!strcmp(name, "Reserved"))
> +		return -EINVAL;
> +
> +	duplicate = kset_find_obj(attribute_kset, name);
> +	if (duplicate) {
> +		pr_debug("Duplicate attribute name found - %s\n", name);
> +		/* kset_find_obj() returns a reference */
> +		kobject_put(duplicate);
> +		return -EBUSY;
> +	}
> +
> +	return 0;
> +}
> +
>  static int tlmi_sysfs_init(void)
>  {
>  	int i, ret;
> @@ -1372,10 +1390,8 @@ static int tlmi_sysfs_init(void)
>  			continue;
> 
>  		/* check for duplicate or reserved values */
> -		if (kset_find_obj(tlmi_priv.attribute_kset, tlmi_priv.setting[i]->display_name) ||
> -		    !strcmp(tlmi_priv.setting[i]->display_name, "Reserved")) {
> -			pr_debug("duplicate or reserved attribute name found - %s\n",
> -				tlmi_priv.setting[i]->display_name);
> +		if (tlmi_validate_setting_name(tlmi_priv.attribute_kset,
> +					       tlmi_priv.setting[i]->display_name) < 0) {
>  			kfree(tlmi_priv.setting[i]->possible_values);
>  			kfree(tlmi_priv.setting[i]);
>  			tlmi_priv.setting[i] = NULL;

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

There seem to be two more of these in hp-bioscfg.

-- 
 i.