[UDP]: Avoid repeated counting of checksum errors due to peeking

Currently it is possible for two processes to peek on the same socket
and end up incrementing the error counter twice for the same packet.

This patch fixes it by making skb_kill_datagram return whether it
succeeded in unlinking the packet and only incrementing the counter
if it did.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 77ab31b99232..87bccec9882a 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -207,8 +207,8 @@ out:
         return err;
 
 csum_copy_err:
-        UDP6_INC_STATS_USER(UDP_MIB_INERRORS, is_udplite);
-        skb_kill_datagram(sk, skb, flags);
+        if (!skb_kill_datagram(sk, skb, flags))
+                UDP6_INC_STATS_USER(UDP_MIB_INERRORS, is_udplite);
 
         if (flags & MSG_DONTWAIT)
                 return -EAGAIN;