[PATCH net-next v2 0/2] 6lowpan: fragmentation fixes

[PATCH net-next v2 0/2] 6lowpan: fragmentation fixes

[Alexander Aring]

This patch series fix the 6LoWPAN fragmentation which are in two cases broken.

The first case is if we have exactly two 6LoWPAN fragments only. This is fixed
by patch "6lowpan_rtnl: fix fragmentation with two fragments".
The second case is a off by one issue if we have payload which hits the fragment
boundary.

Both issues are introduced by commit d4b2816d67d6e07b2f27037f282d8db03a5829d7
("6lowpan: fix fragmentation").

Alexander Aring (2):
  6lowpan_rtnl: fix fragmentation with two fragments
  6lowpan_rtnl: fix off by one while fragmentation

 net/ieee802154/6lowpan_rtnl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
1.9.3

[PATCH net-next v2 1/2] 6lowpan_rtnl: fix fragmentation with two fragments

[Alexander Aring]

This patch fix the 6LoWPAN fragmentation for the case if we have exactly
two fragments. The problem is that the (skb_unprocessed >= frag_cap)
condition is always false on the second fragment after sending the first
fragment. A fragmentation with only one fragment doesn't make any sense.
The solution is that we use a do while loop here, that ensures we sending
always a minimum of two fragments if we need a fragmentation.

This issue was introduced by commit d4b2816d67d6e07b2f27037f282d8db03a5829d7
("6lowpan: fix fragmentation").

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan_rtnl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ieee802154/6lowpan_rtnl.c b/net/ieee802154/6lowpan_rtnl.c
index 1ae8a56..9d57026 100644
--- a/net/ieee802154/6lowpan_rtnl.c
+++ b/net/ieee802154/6lowpan_rtnl.c
@@ -312,7 +312,7 @@ lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *dev,
 	frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
 	frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
 
-	while (skb_unprocessed >= frag_cap) {
+	do {
 		dgram_offset += frag_len;
 		skb_offset += frag_len;
 		skb_unprocessed -= frag_len;
@@ -328,7 +328,7 @@ lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *dev,
 				 __func__, frag_tag, skb_offset);
 			goto err;
 		}
-	}
+	} while (skb_unprocessed >= frag_cap);
 
 	consume_skb(skb);
 	return NET_XMIT_SUCCESS;
-- 
1.9.3

[PATCH net-next v2 2/2] 6lowpan_rtnl: fix off by one while fragmentation

[Alexander Aring]

This patch fix a off by one error while fragmentation. If the frag_cap
value is equal to skb_unprocessed value we need to stop the
fragmentation loop because the last fragment which has a size of
skb_unprocessed fits into the frag capability size.

This issue was introduced by commit d4b2816d67d6e07b2f27037f282d8db03a5829d7
("6lowpan: fix fragmentation").

Signed-off-by: Alexander Aring <alex.aring-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 net/ieee802154/6lowpan_rtnl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ieee802154/6lowpan_rtnl.c b/net/ieee802154/6lowpan_rtnl.c
index 9d57026..fe6bd7a 100644
--- a/net/ieee802154/6lowpan_rtnl.c
+++ b/net/ieee802154/6lowpan_rtnl.c
@@ -328,7 +328,7 @@ lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *dev,
 				 __func__, frag_tag, skb_offset);
 			goto err;
 		}
-	} while (skb_unprocessed >= frag_cap);
+	} while (skb_unprocessed > frag_cap);
 
 	consume_skb(skb);
 	return NET_XMIT_SUCCESS;
-- 
1.9.3


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Re: [PATCH net-next v2 0/2] 6lowpan: fragmentation fixes

[David Miller]

From: Alexander Aring <alex.aring@gmail.com>
Date: Mon,  2 Jun 2014 13:21:56 +0200

> This patch series fix the 6LoWPAN fragmentation which are in two cases broken.
> 
> The first case is if we have exactly two 6LoWPAN fragments only. This is fixed
> by patch "6lowpan_rtnl: fix fragmentation with two fragments".
> The second case is a off by one issue if we have payload which hits the fragment
> boundary.
> 
> Both issues are introduced by commit d4b2816d67d6e07b2f27037f282d8db03a5829d7
> ("6lowpan: fix fragmentation").

Series applied, thanks Alexander.