net: sched: set xt_tgchk_param par.net properly in ipt_init_target

Now xt_tgchk_param par in ipt_init_target is a local varibale,
par.net is not initialized there. Later when xt_check_target
calls target's checkentry in which it may access par.net, it
would cause kernel panic.

Jaroslav found this panic when running:

  # ip link add TestIface type dummy
  # tc qd add dev TestIface ingress handle ffff:
  # tc filter add dev TestIface parent ffff: u32 match u32 0 0 \
    action xt -j CONNMARK --set-mark 4

This patch is to pass net param into ipt_init_target and set
par.net with it properly in there.

v1->v2:
  As Wang Cong pointed, I missed ipt_net_id != xt_net_id, so fix
  it by also passing net_id to __tcf_ipt_init.
v2->v3:
  Missed the fixes tag, so add it.

Fixes: ecb2421b ("netfilter: add and use nf_ct_netns_get/put")
Reported-by: Jaroslav Aster <jaster@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_ipt.c

@@ -36,8 +36,8 @@ static struct tc_action_ops act_ipt_ops;
 static unsigned int xt_net_id;
 static struct tc_action_ops act_xt_ops;
 
-static int ipt_init_target(struct xt_entry_target *t, char *table,
-			   unsigned int hook)
+static int ipt_init_target(struct net *net, struct xt_entry_target *t,
+			   char *table, unsigned int hook)
 {
 	struct xt_tgchk_param par;
 	struct xt_target *target;
@@ -49,6 +49,7 @@ static int ipt_init_target(struct xt_entry_target *t, char *table,
 		return PTR_ERR(target);
 
 	t->u.kernel.target = target;
+	par.net       = net;
 	par.table     = table;
 	par.entryinfo = NULL;
 	par.target    = target;
@@ -91,10 +92,11 @@ static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
 	[TCA_IPT_TARG]	= { .len = sizeof(struct xt_entry_target) },
 };
 
-static int __tcf_ipt_init(struct tc_action_net *tn, struct nlattr *nla,
+static int __tcf_ipt_init(struct net *net, unsigned int id, struct nlattr *nla,
 			  struct nlattr *est, struct tc_action **a,
 			  const struct tc_action_ops *ops, int ovr, int bind)
 {
+	struct tc_action_net *tn = net_generic(net, id);
 	struct nlattr *tb[TCA_IPT_MAX + 1];
 	struct tcf_ipt *ipt;
 	struct xt_entry_target *td, *t;
@@ -159,7 +161,7 @@ static int __tcf_ipt_init(struct tc_action_net *tn, struct nlattr *nla,
 	if (unlikely(!t))
 		goto err2;
 
-	err = ipt_init_target(t, tname, hook);
+	err = ipt_init_target(net, t, tname, hook);
 	if (err < 0)
 		goto err3;
 
@@ -193,18 +195,16 @@ static int tcf_ipt_init(struct net *net, struct nlattr *nla,
 			struct nlattr *est, struct tc_action **a, int ovr,
 			int bind)
 {
-	struct tc_action_net *tn = net_generic(net, ipt_net_id);
-
-	return __tcf_ipt_init(tn, nla, est, a, &act_ipt_ops, ovr, bind);
+	return __tcf_ipt_init(net, ipt_net_id, nla, est, a, &act_ipt_ops, ovr,
+			      bind);
 }
 
 static int tcf_xt_init(struct net *net, struct nlattr *nla,
 		       struct nlattr *est, struct tc_action **a, int ovr,
 		       int bind)
 {
-	struct tc_action_net *tn = net_generic(net, xt_net_id);
-
-	return __tcf_ipt_init(tn, nla, est, a, &act_xt_ops, ovr, bind);
+	return __tcf_ipt_init(net, xt_net_id, nla, est, a, &act_xt_ops, ovr,
+			      bind);
 }
 
 static int tcf_ipt(struct sk_buff *skb, const struct tc_action *a,