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authorEric Dumazet <edumazet@google.com>2016-10-29 11:02:36 -0700
committerDavid S. Miller <davem@davemloft.net>2016-10-31 15:29:11 -0400
commit4f2e4ad56a65f3b7d64c258e373cb71e8d2499f4 (patch)
treebda55b33236870d871bc3402abc8b14f4f262f56 /net
parente551c32d57c88923f99f8f010e89ca7ed0735e83 (diff)
net: mangle zero checksum in skb_checksum_help()
Sending zero checksum is ok for TCP, but not for UDP. UDPv6 receiver should by default drop a frame with a 0 checksum, and UDPv4 would not verify the checksum and might accept a corrupted packet. Simply replace such checksum by 0xffff, regardless of transport. This error was caught on SIT tunnels, but seems generic. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Maciej Żenczykowski <maze@google.com> Cc: Willem de Bruijn <willemb@google.com> Acked-by: Maciej Żenczykowski <maze@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 820bac239738..eaad4c28069f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2484,7 +2484,7 @@ int skb_checksum_help(struct sk_buff *skb)
goto out;
}
- *(__sum16 *)(skb->data + offset) = csum_fold(csum);
+ *(__sum16 *)(skb->data + offset) = csum_fold(csum) ?: CSUM_MANGLED_0;
out_set_summed:
skb->ip_summed = CHECKSUM_NONE;
out: