Re: [PATCH net] qdisc: fix a module refcount leak in qdisc_create_dflt()

From: John Fastabend <john.fastabend@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
	David Miller <davem@davemloft.net>
Cc: netdev <netdev@vger.kernel.org>,
	stephen hemminger <stephen@networkplumber.org>,
	Jamal Hadi Salim <jhs@mojatatu.com>
Subject: Re: [PATCH net] qdisc: fix a module refcount leak in qdisc_create_dflt()
Date: Wed, 24 Aug 2016 10:14:32 -0700	[thread overview]
Message-ID: <57BDD5F8.5080702@gmail.com> (raw)
In-Reply-To: <1472056742.14381.93.camel@edumazet-glaptop3.roam.corp.google.com>

On 16-08-24 09:39 AM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> Should qdisc_alloc() fail, we must release the module refcount
> we got right before.
> 
> Fixes: 6da7c8fcbcbd ("qdisc: allow setting default queuing discipline")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
>  net/sched/sch_generic.c |    9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
> index e95b67cd5718..657c13362b19 100644
> --- a/net/sched/sch_generic.c
> +++ b/net/sched/sch_generic.c
> @@ -643,18 +643,19 @@ struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
>  	struct Qdisc *sch;
>  
>  	if (!try_module_get(ops->owner))
> -		goto errout;
> +		return NULL;
>  
>  	sch = qdisc_alloc(dev_queue, ops);
> -	if (IS_ERR(sch))
> -		goto errout;
> +	if (IS_ERR(sch)) {
> +		module_put(ops->owner);
> +		return NULL;
> +	}
>  	sch->parent = parentid;
>  
>  	if (!ops->init || ops->init(sch, NULL) == 0)
>  		return sch;
>  
>  	qdisc_destroy(sch);
> -errout:
>  	return NULL;
>  }
>  EXPORT_SYMBOL(qdisc_create_dflt);
> 
> 

Thanks!

Acked-by: John Fastabend <john.r.fastabend@intel.com>