From fb74a8416022c033e1a950689c264c453f8f98d8 Mon Sep 17 00:00:00 2001
From: Patrick McHardy <kaber@trash.net>
Date: Tue, 30 Jan 2007 14:24:29 -0800
Subject: [PATCH] [NETFILTER]: xt_connbytes: fix division by zero
When the packet counter of a connection is zero a division by zero
occurs in div64_64(). Fix that by using zero as average value, which
is correct as long as the packet counter didn't overflow, at which
point we have lost anyway.
Additionally we're probably going to go back to 64 bit counters
in 2.6.21.
Based on patch from Jonas Berlin <xkr47@outerspace.dyndns.org>,
with suggestions from KOVACS Krisztian <hidden@balabit.hu>.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/netfilter/xt_connbytes.c | 29 ++++++++++++-----------------
1 file changed, 12 insertions(+), 17 deletions(-)
diff --git a/net/netfilter/xt_connbytes.c b/net/netfilter/xt_connbytes.c
index d93cb096a675c..5e32dfa2668bf 100644
--- a/net/netfilter/xt_connbytes.c
+++ b/net/netfilter/xt_connbytes.c
@@ -52,6 +52,8 @@ match(const struct sk_buff *skb,
{
const struct xt_connbytes_info *sinfo = matchinfo;
u_int64_t what = 0; /* initialize to make gcc happy */
+ u_int64_t bytes = 0;
+ u_int64_t pkts = 0;
const struct ip_conntrack_counter *counters;
if (!(counters = nf_ct_get_counters(skb)))
@@ -89,29 +91,22 @@ match(const struct sk_buff *skb,
case XT_CONNBYTES_AVGPKT:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
- what = div64_64(counters[IP_CT_DIR_ORIGINAL].bytes,
- counters[IP_CT_DIR_ORIGINAL].packets);
+ bytes = counters[IP_CT_DIR_ORIGINAL].bytes;
+ pkts = counters[IP_CT_DIR_ORIGINAL].packets;
break;
case XT_CONNBYTES_DIR_REPLY:
- what = div64_64(counters[IP_CT_DIR_REPLY].bytes,
- counters[IP_CT_DIR_REPLY].packets);
+ bytes = counters[IP_CT_DIR_REPLY].bytes;
+ pkts = counters[IP_CT_DIR_REPLY].packets;
break;
case XT_CONNBYTES_DIR_BOTH:
- {
- u_int64_t bytes;
- u_int64_t pkts;
- bytes = counters[IP_CT_DIR_ORIGINAL].bytes +
- counters[IP_CT_DIR_REPLY].bytes;
- pkts = counters[IP_CT_DIR_ORIGINAL].packets+
- counters[IP_CT_DIR_REPLY].packets;
-
- /* FIXME_THEORETICAL: what to do if sum
- * overflows ? */
-
- what = div64_64(bytes, pkts);
- }
+ bytes = counters[IP_CT_DIR_ORIGINAL].bytes +
+ counters[IP_CT_DIR_REPLY].bytes;
+ pkts = counters[IP_CT_DIR_ORIGINAL].packets +
+ counters[IP_CT_DIR_REPLY].packets;
break;
}
+ if (pkts != 0)
+ what = div64_64(bytes, pkts);
break;
}
--
2.30.2