ipvs: uninitialized data with IP_VS_IPV6

commit 3b05ac38 upstream.

The app_tcp_pkt_out() function expects "*diff" to be set and ends up
using uninitialized data if CONFIG_IP_VS_IPV6 is turned on.

The same issue is there in app_tcp_pkt_in().  Thanks to Julian Anastasov
for noticing that.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
(cherry picked from commit 0ce625ba)
Signed-off-by: Willy Tarreau <w@1wt.eu>

net/netfilter/ipvs/ip_vs_ftp.c

@@ -150,6 +150,8 @@ static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
 	unsigned buf_len;
 	int ret;
 
+	*diff = 0;
+
 #ifdef CONFIG_IP_VS_IPV6
 	/* This application helper doesn't work with IPv6 yet,
 	 * so turn this into a no-op for IPv6 packets
@@ -158,8 +160,6 @@ static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
 		return 1;
 #endif
 
-	*diff = 0;
-
 	/* Only useful for established sessions */
 	if (cp->state != IP_VS_TCP_S_ESTABLISHED)
 		return 1;
@@ -257,6 +257,9 @@ static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp,
 	__be16 port;
 	struct ip_vs_conn *n_cp;
 
+	/* no diff required for incoming packets */
+	*diff = 0;
+
 #ifdef CONFIG_IP_VS_IPV6
 	/* This application helper doesn't work with IPv6 yet,
 	 * so turn this into a no-op for IPv6 packets
@@ -265,9 +268,6 @@ static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp,
 		return 1;
 #endif
 
-	/* no diff required for incoming packets */
-	*diff = 0;
-
 	/* Only useful for established sessions */
 	if (cp->state != IP_VS_TCP_S_ESTABLISHED)
 		return 1;