Merge branch 'net_sched-fix-a-UAF-in-tcf_action_init'

Cong Wang says:

====================
net_sched: fix a UAF in tcf_action_init()

This patchset fixes a use-after-free triggered by syzbot. Please
find more details in each patch description.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/act_api.h

@@ -166,8 +166,6 @@ int tcf_idr_create_from_flags(struct tc_action_net *tn, u32 index,
 			      struct nlattr *est, struct tc_action **a,
 			      const struct tc_action_ops *ops, int bind,
 			      u32 flags);
-void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a);
-
 void tcf_idr_cleanup(struct tc_action_net *tn, u32 index);
 int tcf_idr_check_alloc(struct tc_action_net *tn, u32 *index,
 			struct tc_action **a, int bind);

net/sched/act_api.c

@@ -307,6 +307,8 @@ static int tcf_del_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 
 	mutex_lock(&idrinfo->lock);
 	idr_for_each_entry_ul(idr, p, tmp, id) {
+		if (IS_ERR(p))
+			continue;
 		ret = tcf_idr_release_unsafe(p);
 		if (ret == ACT_P_DELETED) {
 			module_put(ops->owner);
@@ -467,17 +469,6 @@ int tcf_idr_create_from_flags(struct tc_action_net *tn, u32 index,
 }
 EXPORT_SYMBOL(tcf_idr_create_from_flags);
 
-void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a)
-{
-	struct tcf_idrinfo *idrinfo = tn->idrinfo;
-
-	mutex_lock(&idrinfo->lock);
-	/* Replace ERR_PTR(-EBUSY) allocated by tcf_idr_check_alloc */
-	WARN_ON(!IS_ERR(idr_replace(&idrinfo->action_idr, a, a->tcfa_index)));
-	mutex_unlock(&idrinfo->lock);
-}
-EXPORT_SYMBOL(tcf_idr_insert);
-
 /* Cleanup idr index that was allocated but not initialized. */
 
 void tcf_idr_cleanup(struct tc_action_net *tn, u32 index)
@@ -902,6 +893,26 @@ static const struct nla_policy tcf_action_policy[TCA_ACT_MAX + 1] = {
 	[TCA_ACT_HW_STATS]	= NLA_POLICY_BITFIELD32(TCA_ACT_HW_STATS_ANY),
 };
 
+static void tcf_idr_insert_many(struct tc_action *actions[])
+{
+	int i;
+
+	for (i = 0; i < TCA_ACT_MAX_PRIO; i++) {
+		struct tc_action *a = actions[i];
+		struct tcf_idrinfo *idrinfo;
+
+		if (!a)
+			continue;
+		idrinfo = a->idrinfo;
+		mutex_lock(&idrinfo->lock);
+		/* Replace ERR_PTR(-EBUSY) allocated by tcf_idr_check_alloc if
+		 * it is just created, otherwise this is just a nop.
+		 */
+		idr_replace(&idrinfo->action_idr, a, a->tcfa_index);
+		mutex_unlock(&idrinfo->lock);
+	}
+}
+
 struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 				    struct nlattr *nla, struct nlattr *est,
 				    char *name, int ovr, int bind,
@@ -989,6 +1000,13 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 	if (err < 0)
 		goto err_mod;
 
+	if (TC_ACT_EXT_CMP(a->tcfa_action, TC_ACT_GOTO_CHAIN) &&
+	    !rcu_access_pointer(a->goto_chain)) {
+		tcf_action_destroy_1(a, bind);
+		NL_SET_ERR_MSG(extack, "can't use goto chain with NULL chain");
+		return ERR_PTR(-EINVAL);
+	}
+
 	if (!name && tb[TCA_ACT_COOKIE])
 		tcf_set_action_cookie(&a->act_cookie, cookie);
 
@@ -1002,13 +1020,6 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 	if (err != ACT_P_CREATED)
 		module_put(a_o->owner);
 
-	if (TC_ACT_EXT_CMP(a->tcfa_action, TC_ACT_GOTO_CHAIN) &&
-	    !rcu_access_pointer(a->goto_chain)) {
-		tcf_action_destroy_1(a, bind);
-		NL_SET_ERR_MSG(extack, "can't use goto chain with NULL chain");
-		return ERR_PTR(-EINVAL);
-	}
-
 	return a;
 
 err_mod:
@@ -1051,6 +1062,11 @@ int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla,
 		actions[i - 1] = act;
 	}
 
+	/* We have to commit them all together, because if any error happened in
+	 * between, we could not handle the failure gracefully.
+	 */
+	tcf_idr_insert_many(actions);
+
 	*attr_size = tcf_action_full_attrs_size(sz);
 	return i - 1;
 

net/sched/act_bpf.c

@@ -365,9 +365,7 @@ static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 
-	if (res == ACT_P_CREATED) {
+	if (res != ACT_P_CREATED) {
-		tcf_idr_insert(tn, *act);
-	} else {
 		/* make sure the program being replaced is no longer executing */
 		synchronize_rcu();
 		tcf_bpf_cfg_cleanup(&old);

net/sched/act_connmark.c

@@ -139,7 +139,6 @@ static int tcf_connmark_init(struct net *net, struct nlattr *nla,
 		ci->net = net;
 		ci->zone = parm->zone;
 
-		tcf_idr_insert(tn, *a);
 		ret = ACT_P_CREATED;
 	} else if (ret > 0) {
 		ci = to_connmark(*a);

net/sched/act_csum.c

@@ -110,9 +110,6 @@ static int tcf_csum_init(struct net *net, struct nlattr *nla,
 	if (params_new)
 		kfree_rcu(params_new, rcu);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
-
 	return ret;
 put_chain:
 	if (goto_ch)

net/sched/act_ct.c

@@ -1297,8 +1297,6 @@ static int tcf_ct_init(struct net *net, struct nlattr *nla,
 		tcf_chain_put_by_act(goto_ch);
 	if (params)
 		call_rcu(&params->rcu, tcf_ct_params_free);
-	if (res == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 
 	return res;
 

net/sched/act_ctinfo.c

@@ -269,9 +269,6 @@ static int tcf_ctinfo_init(struct net *net, struct nlattr *nla,
 	if (cp_new)
 		kfree_rcu(cp_new, rcu);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
-
 	return ret;
 
 put_chain:

net/sched/act_gact.c

@@ -140,8 +140,6 @@ static int tcf_gact_init(struct net *net, struct nlattr *nla,
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 release_idr:
 	tcf_idr_release(*a, bind);

net/sched/act_gate.c

@@ -437,9 +437,6 @@ static int tcf_gate_init(struct net *net, struct nlattr *nla,
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
-
 	return ret;
 
 chain_put:

net/sched/act_ife.c

@@ -627,9 +627,6 @@ static int tcf_ife_init(struct net *net, struct nlattr *nla,
 	if (p)
 		kfree_rcu(p, rcu);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
-
 	return ret;
 metadata_parse_err:
 	if (goto_ch)

net/sched/act_ipt.c

@@ -189,8 +189,6 @@ static int __tcf_ipt_init(struct net *net, unsigned int id, struct nlattr *nla,
 	ipt->tcfi_t     = t;
 	ipt->tcfi_hook  = hook;
 	spin_unlock_bh(&ipt->tcf_lock);
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 
 err3:

net/sched/act_mirred.c

@@ -194,8 +194,6 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 		spin_lock(&mirred_list_lock);
 		list_add(&m->tcfm_list, &mirred_list);
 		spin_unlock(&mirred_list_lock);
-
-		tcf_idr_insert(tn, *a);
 	}
 
 	return ret;

net/sched/act_mpls.c

@@ -273,8 +273,6 @@ static int tcf_mpls_init(struct net *net, struct nlattr *nla,
 	if (p)
 		kfree_rcu(p, rcu);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 put_chain:
 	if (goto_ch)

net/sched/act_nat.c

@@ -93,9 +93,6 @@ static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
-
 	return ret;
 release_idr:
 	tcf_idr_release(*a, bind);

net/sched/act_pedit.c

@@ -238,8 +238,6 @@ static int tcf_pedit_init(struct net *net, struct nlattr *nla,
 	spin_unlock_bh(&p->tcf_lock);
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 
 put_chain:

net/sched/act_police.c

@@ -201,8 +201,6 @@ static int tcf_police_init(struct net *net, struct nlattr *nla,
 	if (new)
 		kfree_rcu(new, rcu);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 
 failure:

net/sched/act_sample.c

@@ -116,8 +116,6 @@ static int tcf_sample_init(struct net *net, struct nlattr *nla,
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 put_chain:
 	if (goto_ch)

net/sched/act_simple.c

@@ -157,8 +157,6 @@ static int tcf_simp_init(struct net *net, struct nlattr *nla,
 			goto release_idr;
 	}
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 put_chain:
 	if (goto_ch)

net/sched/act_skbedit.c

@@ -225,8 +225,6 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 put_chain:
 	if (goto_ch)

net/sched/act_skbmod.c

@@ -190,8 +190,6 @@ static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 put_chain:
 	if (goto_ch)

net/sched/act_tunnel_key.c

@@ -537,9 +537,6 @@ static int tunnel_key_init(struct net *net, struct nlattr *nla,
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
-
 	return ret;
 
 put_chain:

net/sched/act_vlan.c

@@ -229,8 +229,6 @@ static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 	if (p)
 		kfree_rcu(p, rcu);
 
-	if (ret == ACT_P_CREATED)
-		tcf_idr_insert(tn, *a);
 	return ret;
 put_chain:
 	if (goto_ch)