[Patch net] ife: error out when nla attributes are empty

[Cong Wang]

act_ife at least requires TCA_IFE_PARMS, so we have to bail out
when there is no attribute passed in.

Reported-by: syzbot+fbb5b288c9cb6a2ee...@syzkaller.appspotmail.com
Fixes: ef6980b6becb ("introduce IFE action")
Cc: Jamal Hadi Salim <j...@mojatatu.com>
Cc: Jiri Pirko <j...@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/sched/act_ife.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c
index 41d5398dd2f2..3578196d1600 100644
--- a/net/sched/act_ife.c
+++ b/net/sched/act_ife.c
@@ -481,6 +481,11 @@ static int tcf_ife_init(struct net *net, struct nlattr 
*nla,
        int ret = 0;
        int err;
 
+       if (!nla) {
+               NL_SET_ERR_MSG_MOD(extack, "IFE requires attributes to be 
passed");
+               return -EINVAL;
+       }
+
        err = nla_parse_nested_deprecated(tb, TCA_IFE_MAX, nla, ife_policy,
                                          NULL);
        if (err < 0)
-- 
2.21.0