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

[Hangyu Hua]

On 6/6/2023 16:53, Larysa Zaremba wrote:
> 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.
>
> Code seems reasonable. But commit message is pretty hard to understand.
> Please, replace "corresponding" with "required".
> Also change the first sentence, do not use "can". From what I see, successful
> execution of tcf_proto_lookup_ops always means we now hold reference to module.
>
> CC me in v2, I'll give you Reviewed-by.

I apologize for my incorrect English expression. I will send a v2 later.

Thanks,
Hangyu

> > Fixes: 9f407f1768d3 ("net: sched: introduce chain templates")
> > Signed-off-by: Hangyu Hua <hbh25y@xxxxxxxxx>
> > ---
> >   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