FAILED: patch "[PATCH] netfilter: cttimeout: prevent UAF during module unload" failed to apply to 6.18-stable tree

index 66c2016f6049..132c02ac7c4e 100644
@@ -652,9 +652,9 @@ static void __exit cttimeout_exit(void)
 {
 	nfnetlink_subsys_unregister(&cttimeout_subsys);
 
-	unregister_pernet_subsys(&cttimeout_ops);
 	RCU_INIT_POINTER(nf_ct_timeout_hook, NULL);
 	synchronize_net();
+	unregister_pernet_subsys(&cttimeout_ops);
 }
 
 module_init(cttimeout_init);

index 3a66d4abb6d68..d60aa86be0194 100644
@@ -12,6 +12,7 @@
 #define CTNL_TIMEOUT_NAME_MAX	32
 
 struct nf_ct_timeout {
+	refcount_t		refcnt;
 	__u16			l3num;
 	const struct nf_conntrack_l4proto *l4proto;
 	struct rcu_head		rcu;

@@ -22,6 +23,22 @@ struct nf_conn_timeout {
 	struct nf_ct_timeout __rcu *timeout;
 };
 
+static inline void nf_ct_timeout_put(const struct nf_conn *ct)
+{
+#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
+	struct nf_conn_timeout *timeout_ext;
+	struct nf_ct_timeout *timeout;
+
+	timeout_ext = nf_ct_ext_find(ct, NF_CT_EXT_TIMEOUT);
+	if (!timeout_ext)
+		return;
+
+	timeout = rcu_dereference(timeout_ext->timeout);
+	if (timeout && refcount_dec_and_test(&timeout->refcnt))
+		kfree_rcu(timeout, rcu);
+#endif
+}
+
 static inline unsigned int *
 nf_ct_timeout_data(const struct nf_conn_timeout *t)
 {

@@ -56,8 +73,14 @@ struct nf_conn_timeout *nf_ct_timeout_ext_add(struct nf_conn *ct,
 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 	struct nf_conn_timeout *timeout_ext;
 
+	if (!timeout)
+		return NULL;
+
 	timeout_ext = nf_ct_ext_add(ct, NF_CT_EXT_TIMEOUT, gfp);
-	if (timeout_ext == NULL)
+	if (!timeout_ext || timeout_ext->timeout)
+		return NULL;
+
+	if (!refcount_inc_not_zero(&timeout->refcnt))
 		return NULL;
 
 	rcu_assign_pointer(timeout_ext->timeout, timeout);

@@ -75,7 +98,7 @@ static inline unsigned int *nf_ct_timeout_lookup(const struct nf_conn *ct)
 	struct nf_conn_timeout *timeout_ext;
 
 	timeout_ext = nf_ct_timeout_find(ct);
-	if (timeout_ext)
+	if (timeout_ext && rcu_access_pointer(timeout_ext->timeout))
 		timeouts = nf_ct_timeout_data(timeout_ext);
 #endif
 	return timeouts;

index 44fa3224cc870..201d2ef8a6f02 100644
@@ -1690,16 +1690,18 @@ void nf_conntrack_free(struct nf_conn *ct)
 	 */
 	WARN_ON(refcount_read(&ct->ct_general.use) != 0);
 
+	rcu_read_lock();
 	if (ct->status & IPS_SRC_NAT_DONE) {
 		const struct nf_nat_hook *nat_hook;
 
-		rcu_read_lock();
 		nat_hook = rcu_dereference(nf_nat_hook);
 		if (nat_hook)
 			nat_hook->remove_nat_bysrc(ct);
-		rcu_read_unlock();
 	}
 
+	nf_ct_timeout_put(ct);
+	rcu_read_unlock();
+
 	kfree(ct->ext);
 	kmem_cache_free(nf_conntrack_cachep, ct);
 	cnet = nf_ct_pernet(net);

index 0cc584d3dbb1d..c81becde2afa9 100644
@@ -25,17 +25,32 @@
 const struct nf_ct_timeout_hooks __rcu *nf_ct_timeout_hook __read_mostly;
 EXPORT_SYMBOL_GPL(nf_ct_timeout_hook);
 
+/* nf_ct_iterate_cleanup() holds the conntrack lock. */
 static int untimeout(struct nf_conn *ct, void *timeout)
 {
 	struct nf_conn_timeout *timeout_ext = nf_ct_timeout_find(ct);
 
 	if (timeout_ext) {
-		const struct nf_ct_timeout *t;
+		struct nf_ct_timeout *t;
 
-		t = rcu_access_pointer(timeout_ext->timeout);
+		rcu_read_lock();
+		t = rcu_dereference(timeout_ext->timeout);
+		if (!t) {
+			rcu_read_unlock();
+			return 0;
+		}
 
-		if (!timeout || t == timeout)
+		if (!timeout || t == timeout) {
 			RCU_INIT_POINTER(timeout_ext->timeout, NULL);
+
+			/* No race with nf_conntrack_free() which is called
+			 * only after the conntrack has been removed from
+			 * the hashes.
+			 */
+			if (refcount_dec_and_test(&t->refcnt))
+				kfree_rcu(t, rcu);
+		}
+		rcu_read_unlock();
 	}
 
 	/* We are not intended to delete this conntrack. */

@@ -70,6 +85,8 @@ int nf_ct_set_timeout(struct net *net, struct nf_conn *ct,
 	const char *errmsg = NULL;
 	int ret = 0;
 
+	WARN_ON_ONCE(!nf_ct_is_template(ct));
+
 	rcu_read_lock();
 	h = rcu_dereference(nf_ct_timeout_hook);
 	if (!h) {

@@ -127,6 +144,8 @@ void nf_ct_destroy_timeout(struct nf_conn *ct)
 	struct nf_conn_timeout *timeout_ext;
 	const struct nf_ct_timeout_hooks *h;
 
+	WARN_ON_ONCE(!nf_ct_is_template(ct));
+
 	rcu_read_lock();
 	h = rcu_dereference(nf_ct_timeout_hook);
 

@@ -139,6 +158,8 @@ void nf_ct_destroy_timeout(struct nf_conn *ct)
 			if (t)
 				h->timeout_put(t);
 			RCU_INIT_POINTER(timeout_ext->timeout, NULL);
+			if (t && refcount_dec_and_test(&t->refcnt))
+				kfree_rcu(t, rcu);
 		}
 	}
 	rcu_read_unlock();

219 lines not on this page · raw message

index b29ff555979b2..fa32bbb313065 100644
@@ -898,8 +898,6 @@ static void nft_ct_timeout_obj_eval(struct nft_object *obj,
 		}
 	}
 
-	rcu_assign_pointer(timeout->timeout, priv->timeout);
-
 	/* adjust the timeout as per 'new' state. ct is unconfirmed,
 	 * so the current timestamp must not be added.
 	 */

@@ -950,6 +948,7 @@ static int nft_ct_timeout_obj_init(const struct nft_ctx *ctx,
 
 	timeout->l3num = l3num;
 	timeout->l4proto = l4proto;
+	refcount_set(&timeout->refcnt, 1);
 
 	ret = nf_ct_netns_get(ctx->net, ctx->family);
 	if (ret < 0)

@@ -970,10 +969,10 @@ static void nft_ct_timeout_obj_destroy(const struct nft_ctx *ctx,
 	struct nft_ct_timeout_obj *priv = nft_obj_data(obj);
 	struct nf_ct_timeout *timeout = priv->timeout;
 
-	nf_queue_nf_hook_drop(ctx->net);
 	nf_ct_untimeout(ctx->net, timeout);
 	nf_ct_netns_put(ctx->net, ctx->family);
-	kfree_rcu(priv->timeout, rcu);
+	if (refcount_dec_and_test(&timeout->refcnt))
+		kfree_rcu(priv->timeout, rcu);
 }
 
 static int nft_ct_timeout_obj_dump(struct sk_buff *skb,

index 498f5871c84a0..90a295cf5ec6b 100644
@@ -284,7 +284,7 @@ static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 	struct nf_conn_help *help;
 
 	if (ct) {
-		if (info->helper[0] || info->timeout[0])
+		if (info->helper[0])
 			nf_queue_nf_hook_drop(par->net);
 
 		help = nfct_help(ct);

index c87335d78dfa0..564e4642467dc 100644
@@ -654,9 +654,9 @@ static void __exit cttimeout_exit(void)
 {
 	nfnetlink_subsys_unregister(&cttimeout_subsys);
 
-	unregister_pernet_subsys(&cttimeout_ops);
 	RCU_INIT_POINTER(nf_ct_timeout_hook, NULL);
 	synchronize_net();
+	unregister_pernet_subsys(&cttimeout_ops);
 }
 
 module_init(cttimeout_init);