[PATCH 2/6]: Bug in reading Ack Vectors

[PATCH 2/6]: Bug in reading Ack Vectors

[Gerrit Renker]

[CCID2]: Bug in reading Ack Vectors

In CCID2 the receiver-history is sorted in ascending order of sequence number,
but the processing of received Ack Vectors requires the list traversal in the
opposite direction.

The current code has a bug in this regard: the list traversal is upwards. As a
consequence, only Ack Vectors with a run length of 1 will pass, in all other
Ack Vectors the remaining (acked) sequence numbers are missed, and may later
falsely be identified as lost.

Note: This bug is only visible when Ack Ratio > 1, since otherwise the run
      lengths of Ack Vectors are 0.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
---
 net/dccp/ccids/ccid2.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -666,7 +666,7 @@ static void ccid2_hc_tx_packet_recv(stru
 					done = 1;
 					break;
 				}
-				seqp = seqp->ccid2s_next;
+				seqp = seqp->ccid2s_prev;
 			}
 			if (done)
 				break;

Re: [PATCH 2/6]: Bug in reading Ack Vectors

[Ian McDonald]

On 10/28/07, Gerrit Renker <gerrit@erg.abdn.ac.uk> wrote:
> [CCID2]: Bug in reading Ack Vectors
>
> In CCID2 the receiver-history is sorted in ascending order of sequence number,
> but the processing of received Ack Vectors requires the list traversal in the
> opposite direction.
>
> The current code has a bug in this regard: the list traversal is upwards. As a
> consequence, only Ack Vectors with a run length of 1 will pass, in all other
> Ack Vectors the remaining (acked) sequence numbers are missed, and may later
> falsely be identified as lost.
>
> Note: This bug is only visible when Ack Ratio > 1, since otherwise the run
>       lengths of Ack Vectors are 0.
>
> Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>