linux-kernel - Re: [PATCH v2] EDAC: Fix some refcount leaks

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Message-ID: <YvS97Ixj2cbOBjek@zn.tnic>
Date:   Thu, 11 Aug 2022 10:29:32 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Miaoqian Lin <linmq006@...il.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        James Morse <james.morse@....com>,
        Robert Richter <rric@...nel.org>,
        Greg Kroah-Hartman <gregkh@...e.de>,
        Doug Thompson <dougthompson@...ssion.com>,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] EDAC: Fix some refcount leaks

On Thu, May 12, 2022 at 11:59:06AM +0400, Miaoqian Lin wrote:
> kobject_init_and_add() takes reference even when it fails.
> According to the doc of kobject_init_and_add()
> 
>    If this function returns an error, kobject_put() must be called to
>    properly clean up the memory associated with the object.
> 
> Fix this by calling kobject_put() when kobject_init_and_add() fails.
> 
> Fixes: b2ed215a3338 ("Kobject: change drivers/edac to use kobject_init_and_add")
> Signed-off-by: Miaoqian Lin <linmq006@...il.com>
> ---
> Changes on v2:
> - fix wrong label
> v1 link: https://lore.kernel.org/all/20220511081402.19784-1-linmq006@gmail.com/
> ---
>  drivers/edac/edac_device_sysfs.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/edac/edac_device_sysfs.c b/drivers/edac/edac_device_sysfs.c
> index 9a61d92bdf42..a48142a8ea6f 100644
> --- a/drivers/edac/edac_device_sysfs.c
> +++ b/drivers/edac/edac_device_sysfs.c
> @@ -542,7 +542,7 @@ static int edac_device_create_block(struct edac_device_ctl_info *edac_dev,
>  		edac_dbg(1, "Failed to register instance '%s'\n", block->name);
>  		kobject_put(main_kobj);
>  		err = -ENODEV;
> -		goto err_out;
> +		goto err_on_attrib;
>  	}
>  
>  	/* If there are driver level block attributes, then added them

Actually, on a second look, that's not necessary:

                err = edac_device_create_block(edac_dev, instance,
                                                &instance->blocks[i]);
                if (err) {
                        /* If any fail, remove all previous ones */
                        for (j = 0; j < i; j++)
                                edac_device_delete_block(edac_dev,
                                                        &instance->blocks[j]);
				^^^^^^^^^^^^^^

that cleans up the kobjects.

> @@ -640,7 +640,7 @@ static int edac_device_create_instance(struct edac_device_ctl_info *edac_dev,
>  		edac_dbg(2, "Failed to register instance '%s'\n",
>  			 instance->name);
>  		kobject_put(main_kobj);
> -		goto err_out;
> +		goto err_release_instance_kobj;
>  	}
>  
>  	edac_dbg(4, "now register '%d' blocks for instance %d\n",

Ditto.

But keep lookin' :-)

Thx.

-- 
Regards/Gruss,
    Boris.

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