[PATCH 2.6] netfilter ip_conntrack_irc parser fix

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Hi Dave!

This is the 3rd of my 2.6 merge of the recent bugfixes (all tested
against 2.4.22-pre7). You might need to apply them incrementally
(didn't test it in a different order). You will receive 2.6 merges of
those patches soon.

Author: Harald Welte <laforge@netfilter.org>

This patch fixes a bug in the IRC DCC command parser of ip_conntrack_irc

Please apply,

--- linux-2.6.0-test1/net/ipv4/netfilter/ip_conntrack_irc.c 2003-07-14 05:36:48.000000000 +0200
+++ linux-2.6.0-test1-nftest2/net/ipv4/netfilter/ip_conntrack_irc.c 2003-07-19 11:41:49.000000000 +0200
@@ -54,7 +54,7 @@
 #endif
 
 static char *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " };
-#define MAXMATCHLEN 6
+#define MINMATCHLEN 5
 
 DECLARE_LOCK(ip_irc_lock);
 struct module *ip_conntrack_irc = THIS_MODULE;
@@ -87,9 +87,11 @@
         *ip = simple_strtoul(data, &data, 10);
 
         /* skip blanks between ip and port */
- while (*data == ' ')
+ while (*data == ' ') {
+ if (data >= data_end)
+ return -1;
                 data++;
-
+ }
 
         *port = simple_strtoul(data, &data, 10);
         *ad_end_p = data;
@@ -139,13 +141,17 @@
 
         data = irc_buffer;
         data_limit = irc_buffer + skb->len - dataoff;
- while (data < (data_limit - (22 + MAXMATCHLEN))) {
+
+ /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
+ * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
+ while (data < (data_limit - (19 + MINMATCHLEN))) {
                 if (memcmp(data, "\1DCC ", 5)) {
                         data++;
                         continue;
                 }
 
                 data += 5;
+ /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
 
                 DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n",
                         NIPQUAD(iph->saddr), ntohs(tcph.source),
@@ -159,6 +165,9 @@
 
                         DEBUGP("DCC %s detected\n", dccprotos[i]);
                         data += strlen(dccprotos[i]);
+ /* we have at least
+ * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
+ * data left (== 14/13 bytes) */
                         if (parse_dcc((char *)data, data_limit, &dcc_ip,
                                        &dcc_port, &addr_beg_p, &addr_end_p)) {
                                 /* unable to parse */

-- 
- Harald Welte <laforge@netfilter.org>             http://www.netfilter.org/
============================================================================
  "Fragmentation is like classful addressing -- an interesting early
   architectural error that shows how much experimentation was going
   on while IP was being designed."                    -- Paul Vixie

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