Merge tag 'nf-26-06-10' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf

Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for net:

1) Revalidate bridge ports, add missing NULL checks to fetch the bridge
   device by the port. From Florian Westphal.

2) Fix netdevice refcount leak in the error path of nft_fwd hardware
   offload function, also from Florian.

3) Unregister helper expectfn callback on conntrack helper module
   removal, otherwise dangling pointer remains in place,
   from Weiming Shi.

4) Fix possible pointer infoleak in getsockopt() IPT_SO_GET_ENTRIES,
   From Kyle Zeng.

5) Validate that device MAC header is present before nf_syslog
   accesses it. From Xiang Mei.

6-8) Three patches to address a possible infoleak of stale stack
     data in three nf_tables expressions, due to mismatch in the
     _init() and _eval() function which is possible since 14fb07130c7d.
     From Davide Ornaghi and Florian Westphal.

netfilter pull request 26-06-10

* tag 'nf-26-06-10' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: nft_meta_bridge: fix stale stack leak via IIFHWADDR register
  netfilter: nft_fib: fix stale stack leak via the OIFNAME register
  netfilter: nft_exthdr: fix register tracking for F_PRESENT flag
  netfilter: nf_log: validate MAC header was set before dumping it
  netfilter: x_tables: avoid leaking percpu counter pointers
  netfilter: nf_conntrack: destroy stale expectfn expectations on unregister
  netfilter: nf_tables_offload: drop device refcount on error
  netfilter: revalidate bridge ports
====================

Link: https://patch.msgid.link/20260610161629.214092-1-pablo@netfilter.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

19 files changed, 151 insertions, 51 deletions

diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index de2f956abf34..24cf3d2d9745 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -155,6 +155,7 @@ void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
 
 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
+void nf_ct_helper_expectfn_destroy(const struct nf_ct_helper_expectfn *n);
 struct nf_ct_helper_expectfn *
 nf_ct_helper_expectfn_find_by_name(const char *name);
 struct nf_ct_helper_expectfn *
diff --git a/net/bridge/netfilter/ebt_dnat.c b/net/bridge/netfilter/ebt_dnat.c
index 3fda71a8579d..73f185cccd63 100644
--- a/net/bridge/netfilter/ebt_dnat.c
+++ b/net/bridge/netfilter/ebt_dnat.c
@@ -39,7 +39,9 @@ ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par)
 			dev = xt_in(par);
 			break;
 		case NF_BR_PRE_ROUTING:
-			dev = br_port_get_rcu(xt_in(par))->br->dev;
+			dev = netdev_master_upper_dev_get_rcu(xt_in(par));
+			if (!dev) /* bridge port removed? */
+				return EBT_DROP;
 			break;
 		default:
 			dev = NULL;
diff --git a/net/bridge/netfilter/ebt_redirect.c b/net/bridge/netfilter/ebt_redirect.c
index 307790562b49..83486cd4d564 100644
--- a/net/bridge/netfilter/ebt_redirect.c
+++ b/net/bridge/netfilter/ebt_redirect.c
@@ -24,12 +24,18 @@ ebt_redirect_tg(struct sk_buff *skb, const struct xt_action_param *par)
 	if (skb_ensure_writable(skb, 0))
 		return EBT_DROP;
 
-	if (xt_hooknum(par) != NF_BR_BROUTING)
-		/* rcu_read_lock()ed by nf_hook_thresh */
-		ether_addr_copy(eth_hdr(skb)->h_dest,
-				br_port_get_rcu(xt_in(par))->br->dev->dev_addr);
-	else
+	if (xt_hooknum(par) != NF_BR_BROUTING) {
+		const struct net_device *dev;
+
+		dev = netdev_master_upper_dev_get_rcu(xt_in(par));
+		if (!dev)
+			return EBT_DROP;
+
+		ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
+	} else {
 		ether_addr_copy(eth_hdr(skb)->h_dest, xt_in(par)->dev_addr);
+	}
+
 	skb->pkt_type = PACKET_HOST;
 	return info->target;
 }
diff --git a/net/bridge/netfilter/nft_meta_bridge.c b/net/bridge/netfilter/nft_meta_bridge.c
index 7763e78abb00..219c40680260 100644
--- a/net/bridge/netfilter/nft_meta_bridge.c
+++ b/net/bridge/netfilter/nft_meta_bridge.c
@@ -64,6 +64,8 @@ static void nft_meta_bridge_get_eval(const struct nft_expr *expr,
 		if (!br_dev)
 			goto err;
 
+		/* ETH_ALEN (6) is shorter than the destination register span (8) */
+		dest[1] = 0;
 		memcpy(dest, br_dev->dev_addr, ETH_ALEN);
 		return;
 	default:
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index ad2259678c78..0ea513bf77fb 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -702,14 +702,12 @@ static int copy_entries_to_user(unsigned int total_size,
 		const struct xt_entry_target *t;
 
 		e = loc_cpu_entry + off;
-		if (copy_to_user(userptr + off, e, sizeof(*e))) {
-			ret = -EFAULT;
-			goto free_counters;
-		}
-		if (copy_to_user(userptr + off
+		if (copy_to_user(userptr + off, e,
+				 offsetof(struct arpt_entry, counters)) ||
+		    copy_to_user(userptr + off
 				 + offsetof(struct arpt_entry, counters),
 				 &counters[num],
-				 sizeof(counters[num])) != 0) {
+				 sizeof(counters[num]))) {
 			ret = -EFAULT;
 			goto free_counters;
 		}
@@ -1327,9 +1325,8 @@ static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
 
 	origsize = *size;
 	ce = *dstptr;
-	if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
-	    copy_to_user(&ce->counters, &counters[i],
-	    sizeof(counters[i])) != 0)
+	if (copy_to_user(ce, e, offsetof(struct compat_arpt_entry, counters)) ||
+	    copy_to_user(&ce->counters, &counters[i], sizeof(counters[i])))
 		return -EFAULT;
 
 	*dstptr += sizeof(struct compat_arpt_entry);
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 5cbdb0815857..ca8ff0ae6cdb 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -832,14 +832,12 @@ copy_entries_to_user(unsigned int total_size,
 		const struct xt_entry_target *t;
 
 		e = loc_cpu_entry + off;
-		if (copy_to_user(userptr + off, e, sizeof(*e))) {
-			ret = -EFAULT;
-			goto free_counters;
-		}
-		if (copy_to_user(userptr + off
+		if (copy_to_user(userptr + off, e,
+				 offsetof(struct ipt_entry, counters)) ||
+		    copy_to_user(userptr + off
 				 + offsetof(struct ipt_entry, counters),
 				 &counters[num],
-				 sizeof(counters[num])) != 0) {
+				 sizeof(counters[num]))) {
 			ret = -EFAULT;
 			goto free_counters;
 		}
@@ -1228,9 +1226,8 @@ compat_copy_entry_to_user(struct ipt_entry *e, void __user **dstptr,
 
 	origsize = *size;
 	ce = *dstptr;
-	if (copy_to_user(ce, e, sizeof(struct ipt_entry)) != 0 ||
-	    copy_to_user(&ce->counters, &counters[i],
-	    sizeof(counters[i])) != 0)
+	if (copy_to_user(ce, e, offsetof(struct compat_ipt_entry, counters)) ||
+	    copy_to_user(&ce->counters, &counters[i], sizeof(counters[i])))
 		return -EFAULT;
 
 	*dstptr += sizeof(struct compat_ipt_entry);
diff --git a/net/ipv4/netfilter/nf_nat_h323.c b/net/ipv4/netfilter/nf_nat_h323.c
index faee20af4856..10e1b0837731 100644
--- a/net/ipv4/netfilter/nf_nat_h323.c
+++ b/net/ipv4/netfilter/nf_nat_h323.c
@@ -555,6 +555,8 @@ static void __exit nf_nat_h323_fini(void)
 	nf_ct_helper_expectfn_unregister(&q931_nat);
 	nf_ct_helper_expectfn_unregister(&callforwarding_nat);
 	synchronize_rcu();
+	nf_ct_helper_expectfn_destroy(&q931_nat);
+	nf_ct_helper_expectfn_destroy(&callforwarding_nat);
 }
 
 /****************************************************************************/
diff --git a/net/ipv4/netfilter/nft_fib_ipv4.c b/net/ipv4/netfilter/nft_fib_ipv4.c
index 9d0c6d75109b..177d738825b4 100644
--- a/net/ipv4/netfilter/nft_fib_ipv4.c
+++ b/net/ipv4/netfilter/nft_fib_ipv4.c
@@ -128,7 +128,7 @@ void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
 		fl4.saddr = get_saddr(iph->daddr);
 	}
 
-	*dest = 0;
+	nft_fib_store_result(dest, priv, NULL);
 
 	if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
 		return;
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 9d9c3763f2f5..e34d5ba1460c 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -848,14 +848,12 @@ copy_entries_to_user(unsigned int total_size,
 		const struct xt_entry_target *t;
 
 		e = loc_cpu_entry + off;
-		if (copy_to_user(userptr + off, e, sizeof(*e))) {
-			ret = -EFAULT;
-			goto free_counters;
-		}
-		if (copy_to_user(userptr + off
+		if (copy_to_user(userptr + off, e,
+				 offsetof(struct ip6t_entry, counters)) ||
+		    copy_to_user(userptr + off
 				 + offsetof(struct ip6t_entry, counters),
 				 &counters[num],
-				 sizeof(counters[num])) != 0) {
+				 sizeof(counters[num]))) {
 			ret = -EFAULT;
 			goto free_counters;
 		}
@@ -1244,9 +1242,8 @@ compat_copy_entry_to_user(struct ip6t_entry *e, void __user **dstptr,
 
 	origsize = *size;
 	ce = *dstptr;
-	if (copy_to_user(ce, e, sizeof(struct ip6t_entry)) != 0 ||
-	    copy_to_user(&ce->counters, &counters[i],
-	    sizeof(counters[i])) != 0)
+	if (copy_to_user(ce, e, offsetof(struct compat_ip6t_entry, counters)) ||
+	    copy_to_user(&ce->counters, &counters[i], sizeof(counters[i])))
 		return -EFAULT;
 
 	*dstptr += sizeof(struct compat_ip6t_entry);
diff --git a/net/ipv6/netfilter/nft_fib_ipv6.c b/net/ipv6/netfilter/nft_fib_ipv6.c
index 2dbe44715df3..b9ad7cac1417 100644
--- a/net/ipv6/netfilter/nft_fib_ipv6.c
+++ b/net/ipv6/netfilter/nft_fib_ipv6.c
@@ -239,7 +239,7 @@ void nft_fib6_eval(const struct nft_expr *expr, struct nft_regs *regs,
 
 	lookup_flags = nft_fib6_flowi_init(&fl6, priv, pkt, oif, iph);
 
-	*dest = 0;
+	nft_fib_store_result(dest, priv, NULL);
 	ret = nft_fib6_lookup(nft_net(pkt), &fl6, &res, lookup_flags);
 	if (ret || res.fib6_flags & (RTF_REJECT | RTF_ANYCAST | RTF_LOCAL))
 		return;
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 17e971bd4c74..2c5a71735561 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -283,6 +283,25 @@ void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
 }
 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
 
+static bool expect_iter_expectfn(struct nf_conntrack_expect *exp, void *data)
+{
+	const struct nf_ct_helper_expectfn *n = data;
+
+	/* Relies on registered expectfn descriptors having unique ->expectfn
+	 * pointers, which holds for the in-tree NAT helpers.
+	 */
+	return exp->expectfn == n->expectfn;
+}
+
+/* Destroy expectations still pointing at @n->expectfn; call after the
+ * caller's RCU grace period so none outlives the (often modular) callback.
+ */
+void nf_ct_helper_expectfn_destroy(const struct nf_ct_helper_expectfn *n)
+{
+	nf_ct_expect_iterate_destroy(expect_iter_expectfn, (void *)n);
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_destroy);
+
 /* Caller should hold the rcu lock */
 struct nf_ct_helper_expectfn *
 nf_ct_helper_expectfn_find_by_name(const char *name)
diff --git a/net/netfilter/nf_dup_netdev.c b/net/netfilter/nf_dup_netdev.c
index 3b0a70e154cd..3d88ef927f31 100644
--- a/net/netfilter/nf_dup_netdev.c
+++ b/net/netfilter/nf_dup_netdev.c
@@ -74,16 +74,18 @@ int nft_fwd_dup_netdev_offload(struct nft_offload_ctx *ctx,
 	struct flow_action_entry *entry;
 	struct net_device *dev;
 
-	/* nft_flow_rule_destroy() releases the reference on this device. */
 	dev = dev_get_by_index(ctx->net, oif);
 	if (!dev)
 		return -EOPNOTSUPP;
 
 	entry = nft_flow_action_entry_next(ctx, flow);
-	if (!entry)
+	if (!entry) {
+		dev_put(dev);
 		return -E2BIG;
+	}
 
 	entry->id = id;
+	/* nft_flow_rule_destroy() releases the reference on this device. */
 	entry->dev = dev;
 
 	return 0;
diff --git a/net/netfilter/nf_log_syslog.c b/net/netfilter/nf_log_syslog.c
index 7a8952b049d1..e37b09b3203b 100644
--- a/net/netfilter/nf_log_syslog.c
+++ b/net/netfilter/nf_log_syslog.c
@@ -815,8 +815,8 @@ static void dump_mac_header(struct nf_log_buf *m,
 
 fallback:
 	nf_log_buf_add(m, "MAC=");
-	if (dev->hard_header_len &&
-	    skb->mac_header != skb->network_header) {
+	if (dev->hard_header_len && skb_mac_header_was_set(skb) &&
+	    skb_mac_header_len(skb) != 0) {
 		const unsigned char *p = skb_mac_header(skb);
 		unsigned int i;
 
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 74ec224ce0d6..2bbf5163c0e2 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -1341,6 +1341,7 @@ static int __init nf_nat_init(void)
 		RCU_INIT_POINTER(nf_nat_hook, NULL);
 		nf_ct_helper_expectfn_unregister(&follow_master_nat);
 		synchronize_net();
+		nf_ct_helper_expectfn_destroy(&follow_master_nat);
 		unregister_pernet_subsys(&nat_net_ops);
 		kvfree(nf_nat_bysource);
 	}
@@ -1358,6 +1359,7 @@ static void __exit nf_nat_cleanup(void)
 	RCU_INIT_POINTER(nf_nat_hook, NULL);
 
 	synchronize_net();
+	nf_ct_helper_expectfn_destroy(&follow_master_nat);
 	kvfree(nf_nat_bysource);
 	unregister_pernet_subsys(&nat_net_ops);
 }
diff --git a/net/netfilter/nf_nat_sip.c b/net/netfilter/nf_nat_sip.c
index 9fbfc6bff0c2..00838c0cc5bb 100644
--- a/net/netfilter/nf_nat_sip.c
+++ b/net/netfilter/nf_nat_sip.c
@@ -655,6 +655,7 @@ static void __exit nf_nat_sip_fini(void)
 	RCU_INIT_POINTER(nf_nat_sip_hooks, NULL);
 	nf_ct_helper_expectfn_unregister(&sip_nat);
 	synchronize_rcu();
+	nf_ct_helper_expectfn_destroy(&sip_nat);
 }
 
 static const struct nf_nat_sip_hooks sip_hooks = {
diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index 2439cbbd5b26..fa3657599861 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -451,6 +451,23 @@ nla_put_failure:
 	return -1;
 }
 
+#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
+static int nflog_put_master_ifindex(struct sk_buff *nlskb, int attr,
+				    const struct net_device *dev)
+{
+	const struct net_device *upper;
+
+	if (dev && !netif_is_bridge_port(dev))
+		return 0;
+
+	upper = netdev_master_upper_dev_get_rcu((struct net_device *)dev);
+	if (upper && nla_put_be32(nlskb, attr, htonl(upper->ifindex)))
+		return -EMSGSIZE;
+
+	return 0;
+}
+#endif
+
 /* This is an inline function, we don't really care about a long
  * list of arguments */
 static inline int
@@ -505,8 +522,7 @@ __build_packet_message(struct nfnl_log_net *log,
 			/* rcu_read_lock()ed by nf_hook_thresh or
 			 * nf_log_packet.
 			 */
-			    nla_put_be32(inst->skb, NFULA_IFINDEX_INDEV,
-					 htonl(br_port_get_rcu(indev)->br->dev->ifindex)))
+			    nflog_put_master_ifindex(inst->skb, NFULA_IFINDEX_INDEV, indev))
 				goto nla_put_failure;
 		} else {
 			int physinif;
@@ -542,8 +558,7 @@ __build_packet_message(struct nfnl_log_net *log,
 			/* rcu_read_lock()ed by nf_hook_thresh or
 			 * nf_log_packet.
 			 */
-			    nla_put_be32(inst->skb, NFULA_IFINDEX_OUTDEV,
-					 htonl(br_port_get_rcu(outdev)->br->dev->ifindex)))
+			    nflog_put_master_ifindex(inst->skb, NFULA_IFINDEX_OUTDEV, outdev))
 				goto nla_put_failure;
 		} else {
 			struct net_device *physoutdev;
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 60ab88d45096..c5e29fec419b 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -440,10 +440,47 @@ static bool nf_ct_drop_unconfirmed(const struct nf_queue_entry *entry, bool *is_
 	return false;
 }
 
+static bool nf_bridge_port_valid(const struct net_device *dev)
+{
+	if (!dev)
+		return true;
+
+	return netif_is_bridge_port(dev);
+}
+
+/* queued skbs leave rcu protection.  We bump device refcount so that
+ * the device cannot go away.  However, while packet was out the port
+ * could have been removed from the bridge.
+ *
+ * Ensure in+outdev are still part of a bridge at reinject time.
+ *
+ * The device rx_handler_data could even be pointing at data that is
+ * not a net_bridge_port structure.
+ */
+static bool nf_bridge_ports_valid(const struct nf_queue_entry *entry)
+{
+#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
+	if (!nf_bridge_port_valid(entry->physin) ||
+	    !nf_bridge_port_valid(entry->physout))
+		return false;
+#endif
+	if (entry->state.pf != PF_BRIDGE)
+		return true;
+
+	if (!nf_bridge_port_valid(entry->state.in) ||
+	    !nf_bridge_port_valid(entry->state.out))
+		return false;
+
+	return true;
+}
+
 static void nfqnl_reinject(struct nf_queue_entry *entry, unsigned int verdict)
 {
 	const struct nf_ct_hook *ct_hook;
 
+	if (!nf_bridge_ports_valid(entry))
+		verdict = NF_DROP;
+
 	if (verdict == NF_ACCEPT ||
 	    verdict == NF_REPEAT ||
 	    verdict == NF_STOP) {
@@ -636,6 +673,23 @@ static int nf_queue_checksum_help(struct sk_buff *entskb)
 	return skb_checksum_help(entskb);
 }
 
+#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
+static int nfqnl_put_master_ifindex(struct sk_buff *nlskb, int attr,
+				    const struct net_device *dev)
+{
+	const struct net_device *upper;
+
+	if (dev && !netif_is_bridge_port(dev))
+		return 0;
+
+	upper = netdev_master_upper_dev_get_rcu((struct net_device *)dev);
+	if (upper && nla_put_be32(nlskb, attr, htonl(upper->ifindex)))
+		return -EMSGSIZE;
+
+	return 0;
+}
+#endif
+
 static struct sk_buff *
 nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 			   struct nf_queue_entry *entry,
@@ -771,10 +825,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 			 * netfilter_bridge) */
 			if (nla_put_be32(skb, NFQA_IFINDEX_PHYSINDEV,
 					 htonl(indev->ifindex)) ||
-			/* this is the bridge group "brX" */
-			/* rcu_read_lock()ed by __nf_queue */
-			    nla_put_be32(skb, NFQA_IFINDEX_INDEV,
-					 htonl(br_port_get_rcu(indev)->br->dev->ifindex)))
+			    nfqnl_put_master_ifindex(skb, NFQA_IFINDEX_INDEV, indev))
 				goto nla_put_failure;
 		} else {
 			int physinif;
@@ -805,10 +856,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 			 * netfilter_bridge) */
 			if (nla_put_be32(skb, NFQA_IFINDEX_PHYSOUTDEV,
 					 htonl(outdev->ifindex)) ||
-			/* this is the bridge group "brX" */
-			/* rcu_read_lock()ed by __nf_queue */
-			    nla_put_be32(skb, NFQA_IFINDEX_OUTDEV,
-					 htonl(br_port_get_rcu(outdev)->br->dev->ifindex)))
+			    nfqnl_put_master_ifindex(skb, NFQA_IFINDEX_OUTDEV, outdev))
 				goto nla_put_failure;
 		} else {
 			int physoutif;
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index e6a07c0df207..d3fc7969f123 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -532,6 +532,9 @@ static int nft_exthdr_init(const struct nft_ctx *ctx,
 			return err;
 	}
 
+	if ((flags & NFT_EXTHDR_F_PRESENT) && len != 1)
+		return -EINVAL;
+
 	priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
 	priv->offset = offset;
 	priv->len    = len;
diff --git a/net/netfilter/nft_fib.c b/net/netfilter/nft_fib.c
index 327a5f33659c..a1632e308f18 100644
--- a/net/netfilter/nft_fib.c
+++ b/net/netfilter/nft_fib.c
@@ -107,6 +107,12 @@ int nft_fib_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 		return -EINVAL;
 	}
 
+	if (priv->flags & NFTA_FIB_F_PRESENT) {
+		if (priv->result != NFT_FIB_RESULT_OIF)
+			return -EINVAL;
+		len = sizeof(u8);
+	}
+
 	err = nft_parse_register_store(ctx, tb[NFTA_FIB_DREG], &priv->dreg,
 				       NULL, NFT_DATA_VALUE, len);
 	if (err < 0)