From: "Toke H�d-J�sen" <toke@xxxxxxxxxx>
[ Upstream commit 2867e1eac61016f59b3d730e3f7aa488e186e917 ]
When adding support for propagating ECT(1) marking in IP headers it seems I
suffered from endianness-confusion in the checksum update calculation: In
fact the ECN field is in the *lower* bits of the first 16-bit word of the
IP header when calculating in network byte order. This means that the
addition performed to update the checksum field was wrong; let's fix that.
Fixes: b723748750ec ("tunnel: Propagate ECT(1) when decapsulating as recommended by RFC6040")
Reported-by: Jonathan Morton <chromatix99@xxxxxxxxx>
Tested-by: Pete Heist <pete@xxxxxxxxxx>
Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20201130183705.17540-1-toke@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/inet_ecn.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/net/inet_ecn.h
+++ b/include/net/inet_ecn.h
@@ -107,7 +107,7 @@ static inline int IP_ECN_set_ect1(struct
if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0)
return 0;
- check += (__force u16)htons(0x100);
+ check += (__force u16)htons(0x1);
iph->check = (__force __sum16)(check + (check>=0xFFFF));
iph->tos ^= INET_ECN_MASK;
