Arnaldo,
Haven't seen this going in so resending...
Ian
---------- Forwarded message ----------
From: Ian McDonald <imcdnzl@xxxxxxxxx>
Date: Feb 17, 2006 3:17 PM
Subject: [PATCH] DCCP: Divide by zero fix
To: DCCP Mailing List <dccp@xxxxxxxxxxxxxxx>, Arnaldo Carvalho de Melo
<acme@xxxxxxxxxxxx>
In rare circumstances 0 is returned by dccp_li_hist_calc_i_mean which
leads to a divide by zero in ccid3_hc_rx_packet_recv. Explicitly check
for zero return now. Update copyright notice at same time.
Found by Arnaldo
Signed-off-by: Ian McDonald <imcdnzl@xxxxxxxxx>
----
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 165fc40..fb4db88 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -2,7 +2,7 @@
* net/dccp/ccids/ccid3.c
*
* Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
- * Copyright (c) 2005 Ian McDonald <iam4@xxxxxxxxxxxxxxxx>
+ * Copyright (c) 2005-6 Ian McDonald <imcdnzl@xxxxxxxxx>
*
* An implementation of the DCCP protocol
*
@@ -925,7 +925,7 @@ static void ccid3_hc_rx_packet_recv(stru
struct dccp_rx_hist_entry *packet;
struct timeval now;
u8 win_count;
- u32 p_prev, r_sample, t_elapsed;
+ u32 p_prev, r_sample, t_elapsed, i_mean;
int ins;
BUG_ON(hcrx == NULL ||
@@ -1025,9 +1025,11 @@ static void ccid3_hc_rx_packet_recv(stru
p_prev = hcrx->ccid3hcrx_p;
/* Calculate loss event rate */
- if (!list_empty(&hcrx->ccid3hcrx_li_hist))
+ if (!list_empty(&hcrx->ccid3hcrx_li_hist)) {
+ i_mean = dccp_li_hist_calc_i_mean(&hcrx->ccid3hcrx_li_hist);
+ if (i_mean)
/* Scaling up by 1000000 as fixed decimal */
- hcrx->ccid3hcrx_p = 1000000 /
dccp_li_hist_calc_i_mean(&hcrx->ccid3hcrx_li_hist);
+ hcrx->ccid3hcrx_p = 1000000 / i_mean;
if (hcrx->ccid3hcrx_p > p_prev) {
ccid3_hc_rx_send_feedback(sk);
--
Ian McDonald
Web: http://wand.net.nz/~iam4
Blog: http://imcdnzl.blogspot.com
WAND Network Research Group
Department of Computer Science
University of Waikato
New Zealand
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