6lowpan: Uncompression of traffic class field was incorrect

[ Upstream commit 1188f05497e7bd2f2614b99c54adfbe7413d5749 ]

If priority/traffic class field in IPv6 header is set (seen when
using ssh), the uncompression sets the TC and Flow fields incorrectly.

Example:

This is IPv6 header of a sent packet. Note the priority/TC (=1) in
the first byte.

00000000: 61 00 00 00 00 2c 06 40 fe 80 00 00 00 00 00 00
00000010: 02 02 72 ff fe c6 42 10 fe 80 00 00 00 00 00 00
00000020: 02 1e ab ff fe 4c 52 57

This gets compressed like this in the sending side

00000000: 72 31 04 06 02 1e ab ff fe 4c 52 57 ec c2 00 16
00000010: aa 2d fe 92 86 4e be c6 ....

In the receiving end, the packet gets uncompressed to this
IPv6 header

00000000: 60 06 06 02 00 2a 1e 40 fe 80 00 00 00 00 00 00
00000010: 02 02 72 ff fe c6 42 10 fe 80 00 00 00 00 00 00
00000020: ab ff fe 4c 52 57 ec c2

First four bytes are set incorrectly and we have also lost
two bytes from destination address.

The fix is to switch the case values in switch statement
when checking the TC field.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 55e1fd5b3e56..31b127e8086b 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -862,7 +862,7 @@ lowpan_process_data(struct sk_buff *skb)
          * Traffic class carried in-line
          * ECN + DSCP (1 byte), Flow Label is elided
          */
-        case 1: /* 10b */
+        case 2: /* 10b */
                 if (lowpan_fetch_skb_u8(skb, &tmp))
                         goto drop;
 
@@ -875,7 +875,7 @@ lowpan_process_data(struct sk_buff *skb)
          * Flow Label carried in-line
          * ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
          */
-        case 2: /* 01b */
+        case 1: /* 01b */
                 if (lowpan_fetch_skb_u8(skb, &tmp))
                         goto drop;