Subject: Re: [PATCH net] net: sched: fix possible refcount leak in tc_chain_tmplt_add()

From: Simon Horman <[email-masked]>
Date: Mon, 5 Jun 2023 14:31:10 +0200

On Mon, Jun 05, 2023 at 03:01:58PM +0800, Hangyu Hua wrote:
> try_module_get can be called in tcf_proto_lookup_ops. So if ops don't
> implement the corresponding function we should call module_put to drop
> the refcount.

Hi Hangyu Hua,

Is this correct even if try_module_get() is
not called via tcf_proto_lookup_ops() ?

> Fixes: 9f407f1768d3 ("net: sched: introduce chain templates")
> Signed-off-by: Hangyu Hua <[email-masked]>
> ---
>  net/sched/cls_api.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index 2621550bfddc..92bfb892e638 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -2952,6 +2952,7 @@ static int tc_chain_tmplt_add(struct tcf_chain *chain, struct net *net,
>  		return PTR_ERR(ops);
>  	if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump) {
>  		NL_SET_ERR_MSG(extack, "Chain templates are not supported with specified classifier");
> +		module_put(ops->owner);
>  		return -EOPNOTSUPP;
>  	}
>  
> -- 
> 2.34.1
> 
>