On Wed, 18 Sep 2019 14:37:21 -0700, Cong Wang wrote:
> On Wed, Sep 18, 2019 at 12:57 PM 'Eric Dumazet' via syzkaller
> <syzkal...@googlegroups.com> wrote:
> >
> > If the allocation done in tcf_exts_init() failed,
> > we end up with a NULL pointer in exts->actions.
> ...
> > diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> > index
> > efd3cfb80a2ad775dc8ab3c4900bd73d52c7aaad..9aef93300f1c11791acbb9262dfe77996872eafe
> > 100644
> > --- a/net/sched/cls_api.c
> > +++ b/net/sched/cls_api.c
> > @@ -3027,8 +3027,10 @@ static int tc_dump_chain(struct sk_buff *skb, struct
> > netlink_callback *cb)
> > void tcf_exts_destroy(struct tcf_exts *exts)
> > {
> > #ifdef CONFIG_NET_CLS_ACT
> > - tcf_action_destroy(exts->actions, TCA_ACT_UNBIND);
> > - kfree(exts->actions);
> > + if (exts->actions) {
>
> I think it is _slightly_ better to check exts->nr_actions!=0 here,
> as it would help exts->actions!=NULL&& exts->nr_actions==0
> cases too.
>
> What do you think?
Alternatively, since tcf_exts_destroy() now takes NULL, and so
obviously does kfree() - perhaps tcf_action_destroy() should
return early if actions are NULL?
