Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH 3.12 099/127] net: mangle zero checksum in skb_checksum_help() | Date | Fri, 25 Nov 2016 09:30:12 +0100 |
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From: Eric Dumazet <edumazet@google.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 4f2e4ad56a65f3b7d64c258e373cb71e8d2499f4 ]
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> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- 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 b3788eb33ce4..80468a34ef12 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2263,7 +2263,7 @@ 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: -- 2.10.2
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