* [PATCH net] net: mangle zero checksum in skb_checksum_help()
@ 2016-10-29 18:02 Eric Dumazet
2016-10-29 18:30 ` Maciej Żenczykowski
2016-10-31 19:29 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Eric Dumazet @ 2016-10-29 18:02 UTC (permalink / raw)
To: David Miller; +Cc: netdev, Maciej Żenczykowski, Willem de Bruijn
From: Eric Dumazet <edumazet@google.com>
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>
---
net/core/dev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index dbc871306910..899a0f00e721 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:
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net] net: mangle zero checksum in skb_checksum_help()
2016-10-29 18:02 [PATCH net] net: mangle zero checksum in skb_checksum_help() Eric Dumazet
@ 2016-10-29 18:30 ` Maciej Żenczykowski
2016-10-31 19:29 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Maciej Żenczykowski @ 2016-10-29 18:30 UTC (permalink / raw)
To: Eric Dumazet; +Cc: David Miller, netdev, Willem de Bruijn
Acked-by: Maciej Żenczykowski <maze@google.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net] net: mangle zero checksum in skb_checksum_help()
2016-10-29 18:02 [PATCH net] net: mangle zero checksum in skb_checksum_help() Eric Dumazet
2016-10-29 18:30 ` Maciej Żenczykowski
@ 2016-10-31 19:29 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2016-10-31 19:29 UTC (permalink / raw)
To: eric.dumazet; +Cc: netdev, maze, willemb
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sat, 29 Oct 2016 11:02:36 -0700
> From: Eric Dumazet <edumazet@google.com>
>
> 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>
Applied and queued up for -stable, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-10-31 19:29 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2016-10-29 18:02 [PATCH net] net: mangle zero checksum in skb_checksum_help() Eric Dumazet
2016-10-29 18:30 ` Maciej Żenczykowski
2016-10-31 19:29 ` David Miller
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