Re: nat/conntrack helper locking problem?

[Patrick McHardy <kaber@trash.net>]

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Sorry Harald the last patch added an unneccessary NULL assignment,
this patch is better. It fixes ip_nat_helper_register calling 
ip_ct_find_helper
without holding ip_conntrack_lock.

Best regards,
Patrick

Patrick McHardy wrote:

> It's a relative uncritical error, ip_nat_helper_register races with
> ip_conntrack_helper_unregister. The attached patch should
> fix it.
>


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===== net/ipv4/netfilter/ip_nat_helper.c 1.11 vs edited =====
--- 1.11/net/ipv4/netfilter/ip_nat_helper.c	Mon Oct 13 21:40:48 2003
+++ edited/net/ipv4/netfilter/ip_nat_helper.c	Thu Nov 20 12:57:22 2003
@@ -471,8 +471,11 @@
 	if (me->me && !(me->flags & IP_NAT_HELPER_F_STANDALONE)) {
 		struct ip_conntrack_helper *ct_helper;
 		
-		if ((ct_helper = ip_ct_find_helper(&me->tuple))
-		    && ct_helper->me) {
+		READ_LOCK(&ip_conntrack_lock);
+		ct_helper = ip_ct_find_helper(&me->tuple);
+		READ_UNLOCK(&ip_conntrack_lock);
+
+		if (ct_helper && ct_helper->me) {
 			__MOD_INC_USE_COUNT(ct_helper->me);
 		} else {