1 files changed, 17 insertions, 2 deletions

diff --git a/net/ipv4/xfrm4_protocol.c b/net/ipv4/xfrm4_protocol.c
index 7f7b243e8139..a2ce0101eaac 100644
--- a/net/ipv4/xfrm4_protocol.c
+++ b/net/ipv4/xfrm4_protocol.c
@@ -50,8 +50,12 @@ int xfrm4_rcv_cb(struct sk_buff *skb, u8 protocol, int err)
 {
         int ret;
         struct xfrm4_protocol *handler;
+        struct xfrm4_protocol __rcu **head = proto_handlers(protocol);
 
-        for_each_protocol_rcu(*proto_handlers(protocol), handler)
+        if (!head)
+                return 0;
+
+        for_each_protocol_rcu(*head, handler)
                 if ((ret = handler->cb_handler(skb, err)) <= 0)
                         return ret;
 
@@ -64,15 +68,20 @@ int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
 {
         int ret;
         struct xfrm4_protocol *handler;
+        struct xfrm4_protocol __rcu **head = proto_handlers(nexthdr);
 
         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
         XFRM_SPI_SKB_CB(skb)->family = AF_INET;
         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
 
-        for_each_protocol_rcu(*proto_handlers(nexthdr), handler)
+        if (!head)
+                goto out;
+
+        for_each_protocol_rcu(*head, handler)
                 if ((ret = handler->input_handler(skb, nexthdr, spi, encap_type)) != -EINVAL)
                         return ret;
 
+out:
         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 
         kfree_skb(skb);
@@ -208,6 +217,9 @@ int xfrm4_protocol_register(struct xfrm4_protocol *handler,
         int ret = -EEXIST;
         int priority = handler->priority;
 
+        if (!proto_handlers(protocol) || !netproto(protocol))
+                return -EINVAL;
+
         mutex_lock(&xfrm4_protocol_mutex);
 
         if (!rcu_dereference_protected(*proto_handlers(protocol),
@@ -250,6 +262,9 @@ int xfrm4_protocol_deregister(struct xfrm4_protocol *handler,
         struct xfrm4_protocol *t;
         int ret = -ENOENT;
 
+        if (!proto_handlers(protocol) || !netproto(protocol))
+                return -EINVAL;
+
         mutex_lock(&xfrm4_protocol_mutex);
 
         for (pprev = proto_handlers(protocol);