linux-kernel - Re: [PATCH] EDAC/sysfs: Fix calling kobj_put() with ->state

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Message-ID: <4b715de8-f815-4768-a817-f558ae375955@oracle.com>
Date:   Wed, 29 Nov 2023 00:03:40 +0530
From:   Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
To:     Borislav Petkov <bp@...en8.de>, Tony Luck <tony.luck@...el.com>,
        James Morse <james.morse@....com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Robert Richter <rric@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     dan.carpenter@...aro.org, kernel-janitors@...r.kernel.org,
        error27@...il.com
Subject: Re: [PATCH] EDAC/sysfs: Fix calling kobj_put() with
 ->state_initialized unset

Hi,

On 27/11/23 12:55 pm, Harshit Mogalapalli wrote:
> In edac_device_register_sysfs_main_kobj(), when dev_root is NULL,
> kobject_init_and_add() is not called.
> 
> 	if (err) { // err = -ENODEV
> 		edac_dbg(1, "Failed to register '.../edac/%s'\n",
> 	                 edac_dev->name);
> 		goto err_kobj_reg; // This calls kobj_put()
> 	}
> 
> This will cause a runtime warning in kobject_put() if the above happens.
> Warning:
> "kobject: '%s' (%p): is not initialized, yet kobject_put() is being called."
> 
> Fix the error handling to avoid the above possible situation.
> 
> Fixes: cb4a0bec0bb9 ("EDAC/sysfs: move to use bus_get_dev_root()")
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
> ---

I have sent a v2 as a patch series fixing two very similar bugs:

https://lore.kernel.org/all/20231128183037.3395755-1-harshit.m.mogalapalli@oracle.com/

> This is only compile tested and based on static analysis with Smatch.
> ---
>   drivers/edac/edac_device_sysfs.c | 14 ++++++++------
>   1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/edac/edac_device_sysfs.c b/drivers/edac/edac_device_sysfs.c
> index 010c26be5846..4cac14cbdb60 100644
> --- a/drivers/edac/edac_device_sysfs.c
> +++ b/drivers/edac/edac_device_sysfs.c
> @@ -253,11 +253,13 @@ int edac_device_register_sysfs_main_kobj(struct edac_device_ctl_info *edac_dev)
>   
>   	/* register */
>   	dev_root = bus_get_dev_root(edac_subsys);
> -	if (dev_root) {
> -		err = kobject_init_and_add(&edac_dev->kobj, &ktype_device_ctrl,
> -					   &dev_root->kobj, "%s", edac_dev->name);
> -		put_device(dev_root);
> -	}
> +	if (!dev_root)
> +		goto module_put;
> +
> +	err = kobject_init_and_add(&edac_dev->kobj, &ktype_device_ctrl,
> +				   &dev_root->kobj, "%s", edac_dev->name);
> +	put_device(dev_root);
> +
>   	if (err) {
>   		edac_dbg(1, "Failed to register '.../edac/%s'\n",
>   			 edac_dev->name);
> @@ -276,8 +278,8 @@ int edac_device_register_sysfs_main_kobj(struct edac_device_ctl_info *edac_dev)
>   	/* Error exit stack */
>   err_kobj_reg:
>   	kobject_put(&edac_dev->kobj);
> +module_put:
>   	module_put(edac_dev->owner);
> -
>   err_out:
>   	return err;
>   }