kernel: net_sched: fix a NULL pointer deref in ipt action

The net pointer in struct xt_tgdtor_param is not explicitly
initialized therefore is still NULL when dereferencing it.
So we have to find a way to pass the correct net pointer to
ipt_destroy_target().

The best way I find is just saving the net pointer inside the per
netns struct tcf_idrinfo, which could make this patch smaller.

Fixes: 0c66dc1ea3f0 ("netfilter: conntrack: register hooks in netns when needed by ruleset")
Reported-and-tested-by: Tony Ambardar <itugrok@xxxxxxxxx>
Cc: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Cc: Jiri Pirko <jiri@xxxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

[Backport for kernel v4.19 and v4.14]
[Bug Link: https://bugzilla.kernel.org/show_bug.cgi?id=204681]
Signed-off-by: Tony Ambardar <itugrok@yahoo.com>

1 files changed, 290 insertions, 0 deletions

diff --git a/target/linux/generic/backport-4.19/390-v5.3-net-sched-fix-action-ipt-crash.patch b/target/linux/generic/backport-4.19/390-v5.3-net-sched-fix-action-ipt-crash.patch
new file mode 100644
index 0000000000..3b81d0ec34
--- /dev/null
+++ b/target/linux/generic/backport-4.19/390-v5.3-net-sched-fix-action-ipt-crash.patch
@@ -0,0 +1,290 @@
+From: Cong Wang <xiyou.wangcong@gmail.com>
+To: netdev@vger.kernel.org
+Cc: Cong Wang <xiyou.wangcong@gmail.com>,
+	Tony Ambardar <itugrok@yahoo.com>,
+	Jamal Hadi Salim <jhs@mojatatu.com>,
+	Jiri Pirko <jiri@resnulli.us>
+Subject: [Patch net] net_sched: fix a NULL pointer deref in ipt action
+Date: Sun, 25 Aug 2019 10:01:32 -0700
+
+The net pointer in struct xt_tgdtor_param is not explicitly
+initialized therefore is still NULL when dereferencing it.
+So we have to find a way to pass the correct net pointer to
+ipt_destroy_target().
+
+The best way I find is just saving the net pointer inside the per
+netns struct tcf_idrinfo, which could make this patch smaller.
+
+Fixes: 0c66dc1ea3f0 ("netfilter: conntrack: register hooks in netns when needed by ruleset")
+Reported-and-tested-by: Tony Ambardar <itugrok@yahoo.com>
+Cc: Jamal Hadi Salim <jhs@mojatatu.com>
+Cc: Jiri Pirko <jiri@resnulli.us>
+Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
+
+[Backported for kernel v4.19]
+Signed-off-by: Tony Ambardar <itugrok@yahoo.com>
+---
+ include/net/act_api.h      |  4 +++-
+ net/sched/act_bpf.c        |  2 +-
+ net/sched/act_connmark.c   |  2 +-
+ net/sched/act_csum.c       |  2 +-
+ net/sched/act_gact.c       |  2 +-
+ net/sched/act_ife.c        |  2 +-
+ net/sched/act_ipt.c        | 11 ++++++-----
+ net/sched/act_mirred.c     |  2 +-
+ net/sched/act_nat.c        |  2 +-
+ net/sched/act_pedit.c      |  2 +-
+ net/sched/act_police.c     |  2 +-
+ net/sched/act_sample.c     |  2 +-
+ net/sched/act_simple.c     |  2 +-
+ net/sched/act_skbedit.c    |  2 +-
+ net/sched/act_skbmod.c     |  2 +-
+ net/sched/act_tunnel_key.c |  2 +-
+ net/sched/act_vlan.c       |  2 +-
+ 17 files changed, 24 insertions(+), 21 deletions(-)
+
+--- a/include/net/act_api.h
++++ b/include/net/act_api.h
+@@ -15,6 +15,7 @@
+ struct tcf_idrinfo {
+ 	spinlock_t	lock;
+ 	struct idr	action_idr;
++	struct net	*net;
+ };
+ 
+ struct tc_action_ops;
+@@ -107,7 +108,7 @@ struct tc_action_net {
+ };
+ 
+ static inline
+-int tc_action_net_init(struct tc_action_net *tn,
++int tc_action_net_init(struct net *net, struct tc_action_net *tn,
+ 		       const struct tc_action_ops *ops)
+ {
+ 	int err = 0;
+@@ -116,6 +117,7 @@ int tc_action_net_init(struct tc_action_
+ 	if (!tn->idrinfo)
+ 		return -ENOMEM;
+ 	tn->ops = ops;
++	tn->idrinfo->net = net;
+ 	spin_lock_init(&tn->idrinfo->lock);
+ 	idr_init(&tn->idrinfo->action_idr);
+ 	return err;
+--- a/net/sched/act_bpf.c
++++ b/net/sched/act_bpf.c
+@@ -413,7 +413,7 @@ static __net_init int bpf_init_net(struc
+ {
+ 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
+ 
+-	return tc_action_net_init(tn, &act_bpf_ops);
++	return tc_action_net_init(net, tn, &act_bpf_ops);
+ }
+ 
+ static void __net_exit bpf_exit_net(struct list_head *net_list)
+--- a/net/sched/act_connmark.c
++++ b/net/sched/act_connmark.c
+@@ -215,7 +215,7 @@ static __net_init int connmark_init_net(
+ {
+ 	struct tc_action_net *tn = net_generic(net, connmark_net_id);
+ 
+-	return tc_action_net_init(tn, &act_connmark_ops);
++	return tc_action_net_init(net, tn, &act_connmark_ops);
+ }
+ 
+ static void __net_exit connmark_exit_net(struct list_head *net_list)
+--- a/net/sched/act_csum.c
++++ b/net/sched/act_csum.c
+@@ -678,7 +678,7 @@ static __net_init int csum_init_net(stru
+ {
+ 	struct tc_action_net *tn = net_generic(net, csum_net_id);
+ 
+-	return tc_action_net_init(tn, &act_csum_ops);
++	return tc_action_net_init(net, tn, &act_csum_ops);
+ }
+ 
+ static void __net_exit csum_exit_net(struct list_head *net_list)
+--- a/net/sched/act_gact.c
++++ b/net/sched/act_gact.c
+@@ -263,7 +263,7 @@ static __net_init int gact_init_net(stru
+ {
+ 	struct tc_action_net *tn = net_generic(net, gact_net_id);
+ 
+-	return tc_action_net_init(tn, &act_gact_ops);
++	return tc_action_net_init(net, tn, &act_gact_ops);
+ }
+ 
+ static void __net_exit gact_exit_net(struct list_head *net_list)
+--- a/net/sched/act_ife.c
++++ b/net/sched/act_ife.c
+@@ -887,7 +887,7 @@ static __net_init int ife_init_net(struc
+ {
+ 	struct tc_action_net *tn = net_generic(net, ife_net_id);
+ 
+-	return tc_action_net_init(tn, &act_ife_ops);
++	return tc_action_net_init(net, tn, &act_ife_ops);
+ }
+ 
+ static void __net_exit ife_exit_net(struct list_head *net_list)
+--- a/net/sched/act_ipt.c
++++ b/net/sched/act_ipt.c
+@@ -65,12 +65,13 @@ static int ipt_init_target(struct net *n
+ 	return 0;
+ }
+ 
+-static void ipt_destroy_target(struct xt_entry_target *t)
++static void ipt_destroy_target(struct xt_entry_target *t, struct net *net)
+ {
+ 	struct xt_tgdtor_param par = {
+ 		.target   = t->u.kernel.target,
+ 		.targinfo = t->data,
+ 		.family   = NFPROTO_IPV4,
++		.net      = net,
+ 	};
+ 	if (par.target->destroy != NULL)
+ 		par.target->destroy(&par);
+@@ -82,7 +83,7 @@ static void tcf_ipt_release(struct tc_ac
+ 	struct tcf_ipt *ipt = to_ipt(a);
+ 
+ 	if (ipt->tcfi_t) {
+-		ipt_destroy_target(ipt->tcfi_t);
++		ipt_destroy_target(ipt->tcfi_t, a->idrinfo->net);
+ 		kfree(ipt->tcfi_t);
+ 	}
+ 	kfree(ipt->tcfi_tname);
+@@ -182,7 +183,7 @@ static int __tcf_ipt_init(struct net *ne
+ 
+ 	spin_lock_bh(&ipt->tcf_lock);
+ 	if (ret != ACT_P_CREATED) {
+-		ipt_destroy_target(ipt->tcfi_t);
++		ipt_destroy_target(ipt->tcfi_t, net);
+ 		kfree(ipt->tcfi_tname);
+ 		kfree(ipt->tcfi_t);
+ 	}
+@@ -353,7 +354,7 @@ static __net_init int ipt_init_net(struc
+ {
+ 	struct tc_action_net *tn = net_generic(net, ipt_net_id);
+ 
+-	return tc_action_net_init(tn, &act_ipt_ops);
++	return tc_action_net_init(net, tn, &act_ipt_ops);
+ }
+ 
+ static void __net_exit ipt_exit_net(struct list_head *net_list)
+@@ -403,7 +404,7 @@ static __net_init int xt_init_net(struct
+ {
+ 	struct tc_action_net *tn = net_generic(net, xt_net_id);
+ 
+-	return tc_action_net_init(tn, &act_xt_ops);
++	return tc_action_net_init(net, tn, &act_xt_ops);
+ }
+ 
+ static void __net_exit xt_exit_net(struct list_head *net_list)
+--- a/net/sched/act_mirred.c
++++ b/net/sched/act_mirred.c
+@@ -419,7 +419,7 @@ static __net_init int mirred_init_net(st
+ {
+ 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
+ 
+-	return tc_action_net_init(tn, &act_mirred_ops);
++	return tc_action_net_init(net, tn, &act_mirred_ops);
+ }
+ 
+ static void __net_exit mirred_exit_net(struct list_head *net_list)
+--- a/net/sched/act_nat.c
++++ b/net/sched/act_nat.c
+@@ -317,7 +317,7 @@ static __net_init int nat_init_net(struc
+ {
+ 	struct tc_action_net *tn = net_generic(net, nat_net_id);
+ 
+-	return tc_action_net_init(tn, &act_nat_ops);
++	return tc_action_net_init(net, tn, &act_nat_ops);
+ }
+ 
+ static void __net_exit nat_exit_net(struct list_head *net_list)
+--- a/net/sched/act_pedit.c
++++ b/net/sched/act_pedit.c
+@@ -488,7 +488,7 @@ static __net_init int pedit_init_net(str
+ {
+ 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
+ 
+-	return tc_action_net_init(tn, &act_pedit_ops);
++	return tc_action_net_init(net, tn, &act_pedit_ops);
+ }
+ 
+ static void __net_exit pedit_exit_net(struct list_head *net_list)
+--- a/net/sched/act_police.c
++++ b/net/sched/act_police.c
+@@ -342,7 +342,7 @@ static __net_init int police_init_net(st
+ {
+ 	struct tc_action_net *tn = net_generic(net, police_net_id);
+ 
+-	return tc_action_net_init(tn, &act_police_ops);
++	return tc_action_net_init(net, tn, &act_police_ops);
+ }
+ 
+ static void __net_exit police_exit_net(struct list_head *net_list)
+--- a/net/sched/act_sample.c
++++ b/net/sched/act_sample.c
+@@ -255,7 +255,7 @@ static __net_init int sample_init_net(st
+ {
+ 	struct tc_action_net *tn = net_generic(net, sample_net_id);
+ 
+-	return tc_action_net_init(tn, &act_sample_ops);
++	return tc_action_net_init(net, tn, &act_sample_ops);
+ }
+ 
+ static void __net_exit sample_exit_net(struct list_head *net_list)
+--- a/net/sched/act_simple.c
++++ b/net/sched/act_simple.c
+@@ -215,7 +215,7 @@ static __net_init int simp_init_net(stru
+ {
+ 	struct tc_action_net *tn = net_generic(net, simp_net_id);
+ 
+-	return tc_action_net_init(tn, &act_simp_ops);
++	return tc_action_net_init(net, tn, &act_simp_ops);
+ }
+ 
+ static void __net_exit simp_exit_net(struct list_head *net_list)
+--- a/net/sched/act_skbedit.c
++++ b/net/sched/act_skbedit.c
+@@ -316,7 +316,7 @@ static __net_init int skbedit_init_net(s
+ {
+ 	struct tc_action_net *tn = net_generic(net, skbedit_net_id);
+ 
+-	return tc_action_net_init(tn, &act_skbedit_ops);
++	return tc_action_net_init(net, tn, &act_skbedit_ops);
+ }
+ 
+ static void __net_exit skbedit_exit_net(struct list_head *net_list)
+--- a/net/sched/act_skbmod.c
++++ b/net/sched/act_skbmod.c
+@@ -277,7 +277,7 @@ static __net_init int skbmod_init_net(st
+ {
+ 	struct tc_action_net *tn = net_generic(net, skbmod_net_id);
+ 
+-	return tc_action_net_init(tn, &act_skbmod_ops);
++	return tc_action_net_init(net, tn, &act_skbmod_ops);
+ }
+ 
+ static void __net_exit skbmod_exit_net(struct list_head *net_list)
+--- a/net/sched/act_tunnel_key.c
++++ b/net/sched/act_tunnel_key.c
+@@ -579,7 +579,7 @@ static __net_init int tunnel_key_init_ne
+ {
+ 	struct tc_action_net *tn = net_generic(net, tunnel_key_net_id);
+ 
+-	return tc_action_net_init(tn, &act_tunnel_key_ops);
++	return tc_action_net_init(net, tn, &act_tunnel_key_ops);
+ }
+ 
+ static void __net_exit tunnel_key_exit_net(struct list_head *net_list)
+--- a/net/sched/act_vlan.c
++++ b/net/sched/act_vlan.c
+@@ -324,7 +324,7 @@ static __net_init int vlan_init_net(stru
+ {
+ 	struct tc_action_net *tn = net_generic(net, vlan_net_id);
+ 
+-	return tc_action_net_init(tn, &act_vlan_ops);
++	return tc_action_net_init(net, tn, &act_vlan_ops);
+ }
+ 
+ static void __net_exit vlan_exit_net(struct list_head *net_list)