On Tue, Oct 31, 2017 at 3:09 PM, Cong Wang <xiyou.wangc...@gmail.com> wrote:
>
> This almost rules out the guilty of this patchset.
>
> I will provide a patch for you to test, since I can't reproduce it here.
>

Lucas, please test the attached patch, it applies to latest -net.

Note, it is a combination of 3 patches which together close the
use-after-free you reported here, I hope.

Please let me know if this works. My basic tests run well without
any stack traces or memory leaks.

Thanks!
diff --git a/include/net/act_api.h b/include/net/act_api.h
index b944e0eb93be..c6c8129c3647 100644
--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -13,6 +13,7 @@
 struct tcf_idrinfo {
        spinlock_t      lock;
        struct idr      action_idr;
+       struct net      *net;
 };
 
 struct tc_action_ops;
@@ -100,11 +101,12 @@ struct tc_action_ops {
 struct tc_action_net {
        struct tcf_idrinfo *idrinfo;
        const struct tc_action_ops *ops;
+       struct net *net;
 };
 
 static inline
 int tc_action_net_init(struct tc_action_net *tn,
-                      const struct tc_action_ops *ops)
+                      const struct tc_action_ops *ops, struct net *net)
 {
        int err = 0;
 
@@ -112,6 +114,7 @@ int tc_action_net_init(struct tc_action_net *tn,
        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;
@@ -122,7 +125,9 @@ void tcf_idrinfo_destroy(const struct tc_action_ops *ops,
 
 static inline void tc_action_net_exit(struct tc_action_net *tn)
 {
+       rtnl_lock();
        tcf_idrinfo_destroy(tn->ops, tn->idrinfo);
+       rtnl_unlock();
        kfree(tn->idrinfo);
 }
 
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index da6fa82c98a8..241bf3f925de 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -78,6 +78,7 @@ static void tcf_idr_remove(struct tcf_idrinfo *idrinfo, 
struct tc_action *p)
        spin_lock_bh(&idrinfo->lock);
        idr_remove_ext(&idrinfo->action_idr, p->tcfa_index);
        spin_unlock_bh(&idrinfo->lock);
+       put_net(idrinfo->net);
        gen_kill_estimator(&p->tcfa_rate_est);
        free_tcf(p);
 }
@@ -86,6 +87,8 @@ int __tcf_idr_release(struct tc_action *p, bool bind, bool 
strict)
 {
        int ret = 0;
 
+       ASSERT_RTNL();
+
        if (p) {
                if (bind)
                        p->tcfa_bindcnt--;
@@ -93,7 +96,7 @@ int __tcf_idr_release(struct tc_action *p, bool bind, bool 
strict)
                        return -EPERM;
 
                p->tcfa_refcnt--;
-               if (p->tcfa_bindcnt <= 0 && p->tcfa_refcnt <= 0) {
+               if (p->tcfa_bindcnt == 0 && p->tcfa_refcnt == 0) {
                        if (p->ops->cleanup)
                                p->ops->cleanup(p, bind);
                        tcf_idr_remove(p->idrinfo, p);
@@ -334,6 +337,7 @@ int tcf_idr_create(struct tc_action_net *tn, u32 index, 
struct nlattr *est,
        p->idrinfo = idrinfo;
        p->ops = ops;
        INIT_LIST_HEAD(&p->list);
+       get_net(idrinfo->net);
        *a = p;
        return 0;
 }
diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
index c0c707eb2c96..9bce8cc84cbb 100644
--- a/net/sched/act_bpf.c
+++ b/net/sched/act_bpf.c
@@ -398,7 +398,7 @@ static __net_init int bpf_init_net(struct net *net)
 {
        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(tn, &act_bpf_ops, net);
 }
 
 static void __net_exit bpf_exit_net(struct net *net)
diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
index 10b7a8855a6c..34e52d01a5dd 100644
--- a/net/sched/act_connmark.c
+++ b/net/sched/act_connmark.c
@@ -206,7 +206,7 @@ static __net_init int connmark_init_net(struct net *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(tn, &act_connmark_ops, net);
 }
 
 static void __net_exit connmark_exit_net(struct net *net)
diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
index 1c40caadcff9..35171df2ebef 100644
--- a/net/sched/act_csum.c
+++ b/net/sched/act_csum.c
@@ -626,7 +626,7 @@ static __net_init int csum_init_net(struct net *net)
 {
        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(tn, &act_csum_ops, net);
 }
 
 static void __net_exit csum_exit_net(struct net *net)
diff --git a/net/sched/act_gact.c b/net/sched/act_gact.c
index e29a48ef7fc3..ef7f7f39d26d 100644
--- a/net/sched/act_gact.c
+++ b/net/sched/act_gact.c
@@ -232,7 +232,7 @@ static __net_init int gact_init_net(struct net *net)
 {
        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(tn, &act_gact_ops, net);
 }
 
 static void __net_exit gact_exit_net(struct net *net)
diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c
index 8ccd35825b6b..f65e4b5058e0 100644
--- a/net/sched/act_ife.c
+++ b/net/sched/act_ife.c
@@ -818,7 +818,7 @@ static __net_init int ife_init_net(struct net *net)
 {
        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(tn, &act_ife_ops, net);
 }
 
 static void __net_exit ife_exit_net(struct net *net)
diff --git a/net/sched/act_ipt.c b/net/sched/act_ipt.c
index d9e399a7e3d5..dbdf3b2470d5 100644
--- a/net/sched/act_ipt.c
+++ b/net/sched/act_ipt.c
@@ -334,7 +334,7 @@ static __net_init int ipt_init_net(struct net *net)
 {
        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(tn, &act_ipt_ops, net);
 }
 
 static void __net_exit ipt_exit_net(struct net *net)
@@ -384,7 +384,7 @@ static __net_init int xt_init_net(struct net *net)
 {
        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(tn, &act_xt_ops, net);
 }
 
 static void __net_exit xt_exit_net(struct net *net)
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 416627c66f08..84759cfd5a33 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -343,7 +343,7 @@ static __net_init int mirred_init_net(struct net *net)
 {
        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(tn, &act_mirred_ops, net);
 }
 
 static void __net_exit mirred_exit_net(struct net *net)
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index c365d01b99c8..7eeaaf9217b6 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -307,7 +307,7 @@ static __net_init int nat_init_net(struct net *net)
 {
        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(tn, &act_nat_ops, net);
 }
 
 static void __net_exit nat_exit_net(struct net *net)
diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c
index 491fe5deb09e..b3d82c334a5f 100644
--- a/net/sched/act_pedit.c
+++ b/net/sched/act_pedit.c
@@ -450,7 +450,7 @@ static __net_init int pedit_init_net(struct net *net)
 {
        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(tn, &act_pedit_ops, net);
 }
 
 static void __net_exit pedit_exit_net(struct net *net)
diff --git a/net/sched/act_police.c b/net/sched/act_police.c
index 3bb2ebf9e9ae..9ec42b26e4b9 100644
--- a/net/sched/act_police.c
+++ b/net/sched/act_police.c
@@ -331,7 +331,7 @@ static __net_init int police_init_net(struct net *net)
 {
        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(tn, &act_police_ops, net);
 }
 
 static void __net_exit police_exit_net(struct net *net)
diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c
index a9f9a2ccc664..71b8405e9718 100644
--- a/net/sched/act_sample.c
+++ b/net/sched/act_sample.c
@@ -240,7 +240,7 @@ static __net_init int sample_init_net(struct net *net)
 {
        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(tn, &act_sample_ops, net);
 }
 
 static void __net_exit sample_exit_net(struct net *net)
diff --git a/net/sched/act_simple.c b/net/sched/act_simple.c
index e7b57e5071a3..a8d0ea95f894 100644
--- a/net/sched/act_simple.c
+++ b/net/sched/act_simple.c
@@ -201,7 +201,7 @@ static __net_init int simp_init_net(struct net *net)
 {
        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(tn, &act_simp_ops, net);
 }
 
 static void __net_exit simp_exit_net(struct net *net)
diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c
index 59949d61f20d..fbac62472e09 100644
--- a/net/sched/act_skbedit.c
+++ b/net/sched/act_skbedit.c
@@ -238,7 +238,7 @@ static __net_init int skbedit_init_net(struct net *net)
 {
        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(tn, &act_skbedit_ops, net);
 }
 
 static void __net_exit skbedit_exit_net(struct net *net)
diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c
index b642ad3d39dd..8e12d8897d2f 100644
--- a/net/sched/act_skbmod.c
+++ b/net/sched/act_skbmod.c
@@ -263,7 +263,7 @@ static __net_init int skbmod_init_net(struct net *net)
 {
        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(tn, &act_skbmod_ops, net);
 }
 
 static void __net_exit skbmod_exit_net(struct net *net)
diff --git a/net/sched/act_tunnel_key.c b/net/sched/act_tunnel_key.c
index 30c96274c638..c33faa373cf2 100644
--- a/net/sched/act_tunnel_key.c
+++ b/net/sched/act_tunnel_key.c
@@ -322,7 +322,7 @@ static __net_init int tunnel_key_init_net(struct net *net)
 {
        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(tn, &act_tunnel_key_ops, net);
 }
 
 static void __net_exit tunnel_key_exit_net(struct net *net)
diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c
index 16eb067a8d8f..115fc33cc6d8 100644
--- a/net/sched/act_vlan.c
+++ b/net/sched/act_vlan.c
@@ -269,7 +269,7 @@ static __net_init int vlan_init_net(struct net *net)
 {
        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(tn, &act_vlan_ops, net);
 }
 
 static void __net_exit vlan_exit_net(struct net *net)

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