ipv[4|6]: correct dropwatch false positive in local_deliver_finish

I had a report recently of a user trying to use dropwatch to localise some frame
loss, and they were getting false positives.  Turned out they were using a user
space SCTP stack that used raw sockets to grab frames.  When we don't have a
registered protocol for a given packet, we record it as a drop, even if a raw
socket receieves the frame.  We should only record the drop in the event a raw
socket doesnt exist to receive the frames

Tested by the reported successfully

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reported-by: William Reich <reich@ulticom.com>
Tested-by: William Reich <reich@ulticom.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: William Reich <reich@ulticom.com>
CC: eric.dumazet@gmail.com
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 87abd3e..2bdf802 100644 (file)
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -228,9 +228,11 @@ static int ip_local_deliver_finish(struct sk_buff *skb)
                                        icmp_send(skb, ICMP_DEST_UNREACH,
                                                  ICMP_PROT_UNREACH, 0);
                                }
-                       } else
+                               kfree_skb(skb);
+                       } else {
                                IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
-                       kfree_skb(skb);
+                               consume_skb(skb);
+                       }
                }
        }
  out:

diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 5b10414..b1876e5 100644 (file)
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -241,9 +241,11 @@ resubmit:
                                icmpv6_send(skb, ICMPV6_PARAMPROB,
                                            ICMPV6_UNK_NEXTHDR, nhoff);
                        }
-               } else
+                       kfree_skb(skb);
+               } else {
                        IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
-               kfree_skb(skb);
+                       consume_skb(skb);
+               }
        }
        rcu_read_unlock();
        return 0;