[NETFILTER] NAT: Fix module refcount dropping too far

The unknown protocol is used as a fallback when a protocol isn't known.
Hence we cannot handle it failing, so don't set ".me".  It's OK, since we
only grab a reference from within the same module (iptable_nat.ko), so we
never take the module refcount from 0 to 1.

Also, remove the "protocol is NULL" test: it's never NULL.

Signed-off-by: Rusty Rusty <rusty@rustcorp.com.au>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

2 files changed, 3 insertions, 5 deletions

diff --git a/net/ipv4/netfilter/ip_nat_core.c b/net/ipv4/netfilter/ip_nat_core.c
index c5e3abd24672..762f4d93936b 100644
--- a/net/ipv4/netfilter/ip_nat_core.c
+++ b/net/ipv4/netfilter/ip_nat_core.c
@@ -66,10 +66,8 @@ ip_nat_proto_find_get(u_int8_t protonum)
          * removed until we've grabbed the reference */
         preempt_disable();
         p = __ip_nat_proto_find(protonum);
-        if (p) {
-                if (!try_module_get(p->me))
-                        p = &ip_nat_unknown_protocol;
-        }
+        if (!try_module_get(p->me))
+                p = &ip_nat_unknown_protocol;
         preempt_enable();
 
         return p;
diff --git a/net/ipv4/netfilter/ip_nat_proto_unknown.c b/net/ipv4/netfilter/ip_nat_proto_unknown.c
index 99bbef56f84e..f0099a646a0b 100644
--- a/net/ipv4/netfilter/ip_nat_proto_unknown.c
+++ b/net/ipv4/netfilter/ip_nat_proto_unknown.c
@@ -62,7 +62,7 @@ unknown_print_range(char *buffer, const struct ip_nat_range *range)
 
 struct ip_nat_protocol ip_nat_unknown_protocol = {
         .name                   = "unknown",
-        .me                     = THIS_MODULE,
+        /* .me isn't set: getting a ref to this cannot fail. */
         .manip_pkt              = unknown_manip_pkt,
         .in_range               = unknown_in_range,
         .unique_tuple           = unknown_unique_tuple,