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

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Message-ID: <8e1592dd-7e95-20a6-15e7-f21798af3d37@lenovo.com>
Date:   Mon, 25 Sep 2023 10:00:02 -0400
From:   Mark Pearson <markpearson@...ovo.com>
To:     Armin Wolf <W_Armin@....de>
CC:     <hdegoede@...hat.com>, <markgross@...nel.org>,
        <ilpo.jarvinen@...ux.intel.com>,
        <platform-driver-x86@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [External] [PATCH] platform/x86: think-lmi: Fix reference leak

Thanks Armin,

On 9/23/23 16:41, 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;
> --
> 2.39.2
>

Reviewed-by: Mark Pearson <mpearson-lenovo@...ebb.ca>

Do you have any reports of our platforms where these are seen? If so I'd like to get it fixed in FW too (and I can get it tested on HW if that helps)

Mark