netfilter: xt_socket: fix broken v0 support

commit 681f130f39e10 ("netfilter: xt_socket: add XT_SOCKET_NOWILDCARD
flag") added a potential NULL dereference if an old iptables package
uses v0 of the match.

Fix this by removing the test on @info in fast path.

IPv6 can remove the test as well, as it uses v1 or v2.

Reported-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
index f8b71911037ab172f3df8f6a82cb8d22191ab1d6..20b15916f40363ff789d2d7312dd5fe4dedf69ab 100644 (file)
--- a/net/netfilter/xt_socket.c
+++ b/net/netfilter/xt_socket.c
@@ -172,7 +172,7 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
 
                /* Ignore non-transparent sockets,
                   if XT_SOCKET_TRANSPARENT is used */
-               if (info && info->flags & XT_SOCKET_TRANSPARENT)
+               if (info->flags & XT_SOCKET_TRANSPARENT)
                        transparent = ((sk->sk_state != TCP_TIME_WAIT &&
                                        inet_sk(sk)->transparent) ||
                                       (sk->sk_state == TCP_TIME_WAIT &&
@@ -196,7 +196,11 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
 static bool
 socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par)
 {
-       return socket_match(skb, par, NULL);
+       static struct xt_socket_mtinfo1 xt_info_v0 = {
+               .flags = 0,
+       };
+
+       return socket_match(skb, par, &xt_info_v0);
 }
 
 static bool
@@ -314,7 +318,7 @@ socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
 
                /* Ignore non-transparent sockets,
                   if XT_SOCKET_TRANSPARENT is used */
-               if (info && info->flags & XT_SOCKET_TRANSPARENT)
+               if (info->flags & XT_SOCKET_TRANSPARENT)
                        transparent = ((sk->sk_state != TCP_TIME_WAIT &&
                                        inet_sk(sk)->transparent) ||
                                       (sk->sk_state == TCP_TIME_WAIT &&