Commit 1188f054 authored Nov 13, 2013 by Jukka Rissanen Committed by David S. Miller Nov 15, 2013

6lowpan: Uncompression of traffic class field was incorrect



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>

parent 3db0a197

net/ieee802154/6lowpan.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -956,7 +956,7 @@ 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;

		@@ -967,7 +967,7 @@ 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;

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