linux-kernel - Re: [PATCH] mm: Fix kobject memleak in SLUB

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Date:   Wed, 1 May 2019 08:54:18 +1000
From:   "Tobin C. Harding" <me@...in.cc>
To:     "Tobin C. Harding" <tobin@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: Fix kobject memleak in SLUB

On Sun, Apr 28, 2019 at 09:40:00AM +1000, Tobin C. Harding wrote:
> Currently error return from kobject_init_and_add() is not followed by a
> call to kobject_put().  This means there is a memory leak.
> 
> Add call to kobject_put() in error path of kobject_init_and_add().
> 
> Signed-off-by: Tobin C. Harding <tobin@...nel.org>
> ---
>  mm/slub.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index d30ede89f4a6..84a9d6c06c27 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -5756,8 +5756,10 @@ static int sysfs_slab_add(struct kmem_cache *s)
>  
>  	s->kobj.kset = kset;
>  	err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
> -	if (err)
> +	if (err) {
> +		kobject_put(&s->kobj);
>  		goto out;
> +	}
>  
>  	err = sysfs_create_group(&s->kobj, &slab_attr_group);
>  	if (err)
> -- 
> 2.21.0
> 

This patch is not _completely_ correct.  Please do not consider for
merge.  There are a bunch of these on various LKML lists, once the
confusion has cleared I'll re-spin v2.

thanks,
Tobin.