[NETFILTER]: nf_nat: Clears helper private area when NATing

Some helpers (eg. ftp) assume that private area in conntrack is
filled with zero. It should be cleared when helper is changed.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 94000a4c7dcf..e8b5c2d7db62 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -888,8 +888,13 @@ void nf_conntrack_alter_reply(struct nf_conn *ct,
         NF_CT_DUMP_TUPLE(newreply);
 
         ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply;
-        if (!ct->master && help && help->expecting == 0)
-                help->helper = __nf_ct_helper_find(newreply);
+        if (!ct->master && help && help->expecting == 0) {
+                struct nf_conntrack_helper *helper;
+                helper = __nf_ct_helper_find(newreply);
+                if (helper)
+                        memset(&help->help, 0, sizeof(help->help));
+                help->helper = helper;
+        }
         write_unlock_bh(&nf_conntrack_lock);
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);