netdev - Re: Netfilter: kernel panic with REDIRECT target. (2.6.23 and 2.6.23.8)

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Date:	Tue, 20 Nov 2007 14:55:20 +0300
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	David <david@...olicited.net>
Cc:	Patrick McHardy <kaber@...sh.net>,
	Ismail Dönmez <ismail@...dus.org.tr>,
	netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: Netfilter: kernel panic with REDIRECT target. (2.6.23 and 2.6.23.8)

> >> Ok, let's try it hard way.
> >> Please check attached patch and tell if it helped (it will produce
> >> some debug though).
> >
> > With both patches applied - one Patrick showed and this one.
> >   
> Now works, with this in dmesg
> 
> conntrack: ea94159c, new: ead4d7c4, old: ead4d7d0, ct: 00000000.

David (Miller :), please apply attached patch, which also needed to fix
netfilter connection tracking bug.
When connection tracking entry (nf_conn) is about to copy itself it can
have some of its extension users (like nat) as being already freed and
thus not required to be copied.
Frankly saying, it can be not the correct fix, but from code observation
and test, perfomed by David <david@...olicited.net> it is.

Actually looking at this function I suspect it was copied from
nf_nat_setup_info() and thus bug was introduced.

Signed-off-by: Evgeniy Polyakov <johnpol@....mipt.ru>

diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index 70e7997..86b465b 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -607,13 +607,10 @@ static void nf_nat_move_storage(struct nf_conn *conntrack, void *old)
 	struct nf_conn_nat *new_nat = nf_ct_ext_find(conntrack, NF_CT_EXT_NAT);
 	struct nf_conn_nat *old_nat = (struct nf_conn_nat *)old;
 	struct nf_conn *ct = old_nat->ct;
-	unsigned int srchash;
 
-	if (!(ct->status & IPS_NAT_DONE_MASK))
+	if (!ct || !(ct->status & IPS_NAT_DONE_MASK))
 		return;
 
-	srchash = hash_by_src(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
-
 	write_lock_bh(&nf_nat_lock);
 	hlist_replace_rcu(&old_nat->bysource, &new_nat->bysource);
 	new_nat->ct = ct;

-- 
	Evgeniy Polyakov
-
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