From f2c06f0484a15d0779ab998953e8e2cc82e976c9 Mon Sep 17 00:00:00 2001
From: Patrick McHardy <kaber@trash.net>
Date: Fri, 25 Jul 2003 01:18:17 -0700
Subject: [PATCH] [NETFILTER]: Fix locking of ipt_helper.

---
 net/ipv4/netfilter/ipt_helper.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/netfilter/ipt_helper.c b/net/ipv4/netfilter/ipt_helper.c
index 1f7efb91c5e8c..28ab46445e4a9 100644
--- a/net/ipv4/netfilter/ipt_helper.c
+++ b/net/ipv4/netfilter/ipt_helper.c
@@ -10,6 +10,7 @@
 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <linux/netfilter_ipv4/ip_conntrack.h>
+#include <linux/netfilter_ipv4/ip_conntrack_core.h>
 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
 #include <linux/netfilter_ipv4/ip_tables.h>
 #include <linux/netfilter_ipv4/ipt_helper.h>
@@ -34,6 +35,7 @@ match(const struct sk_buff *skb,
 	struct ip_conntrack_expect *exp;
 	struct ip_conntrack *ct;
 	enum ip_conntrack_info ctinfo;
+	int ret = 0;
 	
 	ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo);
 	if (!ct) {
@@ -47,23 +49,27 @@ match(const struct sk_buff *skb,
 	}
 
 	exp = ct->master;
+	READ_LOCK(&ip_conntrack_lock);
 	if (!exp->expectant) {
 		DEBUGP("ipt_helper: expectation %p without expectant !?!\n", 
 			exp);
-		return 0;
+		goto out_unlock;
 	}
 
 	if (!exp->expectant->helper) {
 		DEBUGP("ipt_helper: master ct %p has no helper\n", 
 			exp->expectant);
-		return 0;
+		goto out_unlock;
 	}
 
 	DEBUGP("master's name = %s , info->name = %s\n", 
 		exp->expectant->helper->name, info->name);
 
-	return !strncmp(exp->expectant->helper->name, info->name, 
-			strlen(exp->expectant->helper->name)) ^ info->invert;
+	ret = !strncmp(exp->expectant->helper->name, info->name, 
+	               strlen(exp->expectant->helper->name)) ^ info->invert;
+out_unlock:
+	READ_UNLOCK(&ip_conntrack_lock);
+	return ret;
 }
 
 static int check(const char *tablename,
-- 
2.53.0