[ovs-dev] [PATCH 1/3] datapath: compat: fix udp checksum calculation

[Pravin B Shelar]

In upstream linux kernel networking stack udp_set_csum() is called
with only udp header applied but in case of compat layer it can
be called with IP header. So following patch take the offset into
account.

Signed-off-by: Pravin B Shelar <pshelar at ovn.org>
---
 datapath/linux/compat/udp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/datapath/linux/compat/udp.c b/datapath/linux/compat/udp.c
index f0362b6..0152830 100644
--- a/datapath/linux/compat/udp.c
+++ b/datapath/linux/compat/udp.c
@@ -26,12 +26,13 @@ void rpl_udp_set_csum(bool nocheck, struct sk_buff *skb,
 		skb->csum_offset = offsetof(struct udphdr, check);
 		uh->check = ~udp_v4_check(len, saddr, daddr, 0);
 	} else {
+		int l4_offset = skb_transport_offset(skb);
 		__wsum csum;
 
 		BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL);
 
 		uh->check = 0;
-		csum = skb_checksum(skb, 0, len, 0);
+		csum = skb_checksum(skb, l4_offset, len, 0);
 		uh->check = udp_v4_check(len, saddr, daddr, csum);
 		if (uh->check == 0)
 			uh->check = CSUM_MANGLED_0;
-- 
1.9.1