netfilter: xtables: compat out of scope fix

As per C99 6.2.4(2) when temporary table data goes out of scope,
the behaviour is undefined:

	if (compat) {
		struct foo tmp;
		...
		private = &tmp;
	}
	[dereference private]

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Patrick McHardy <kaber@trash.net>

3 files changed, 6 insertions, 6 deletions

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 06632762ba5f..90203e1b9187 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -925,10 +925,10 @@ static int get_info(struct net *net, void __user *user, int *len, int compat)
         if (t && !IS_ERR(t)) {
                 struct arpt_getinfo info;
                 const struct xt_table_info *private = t->private;
-
 #ifdef CONFIG_COMPAT
+                struct xt_table_info tmp;
+
                 if (compat) {
-                        struct xt_table_info tmp;
                         ret = compat_table_info(private, &tmp);
                         xt_compat_flush_offsets(NFPROTO_ARP);
                         private = &tmp;
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 572330a552ef..3ce53cf13d5a 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1132,10 +1132,10 @@ static int get_info(struct net *net, void __user *user, int *len, int compat)
         if (t && !IS_ERR(t)) {
                 struct ipt_getinfo info;
                 const struct xt_table_info *private = t->private;
-
 #ifdef CONFIG_COMPAT
+                struct xt_table_info tmp;
+
                 if (compat) {
-                        struct xt_table_info tmp;
                         ret = compat_table_info(private, &tmp);
                         xt_compat_flush_offsets(AF_INET);
                         private = &tmp;
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 480d7f8c9802..8a7e0f52e177 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1164,10 +1164,10 @@ static int get_info(struct net *net, void __user *user, int *len, int compat)
         if (t && !IS_ERR(t)) {
                 struct ip6t_getinfo info;
                 const struct xt_table_info *private = t->private;
-
 #ifdef CONFIG_COMPAT
+                struct xt_table_info tmp;
+
                 if (compat) {
-                        struct xt_table_info tmp;
                         ret = compat_table_info(private, &tmp);
                         xt_compat_flush_offsets(AF_INET6);
                         private = &tmp;