netfilter: nf_conntrack: padding breaks conntrack hash on ARM

commit 0794935e "[NETFILTER]: nf_conntrack: optimize hash_conntrack()"
results in ARM platforms hashing uninitialised padding. This padding
doesn't exist on other architectures.

Fix this by replacing NF_CT_TUPLE_U_BLANK() with memset() to ensure
everything is initialised. There were only 4 bytes that
NF_CT_TUPLE_U_BLANK() wasn't clearing anyway (or 12 bytes on ARM).

Signed-off-by: Philip Craig <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/netfilter/nf_conntrack_tuple.h

···
 	} src;
 };
 
-/* This is optimized opposed to a memset of the whole structure.  Everything we
- * really care about is the  source/destination unions */
-#define NF_CT_TUPLE_U_BLANK(tuple)                              	\
-        do {                                                    	\
-                (tuple)->src.u.all = 0;                         	\
-                (tuple)->dst.u.all = 0;                         	\
-		memset(&(tuple)->src.u3, 0, sizeof((tuple)->src.u3));	\
-		memset(&(tuple)->dst.u3, 0, sizeof((tuple)->dst.u3));	\
-        } while (0)
-
 #ifdef __KERNEL__
 
 static inline void nf_ct_dump_tuple_ip(const struct nf_conntrack_tuple *t)

net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c

···
 	const struct nf_conntrack_tuple_hash *h;
 	struct nf_conntrack_tuple tuple;
 
-	NF_CT_TUPLE_U_BLANK(&tuple);
+	memset(&tuple, 0, sizeof(tuple));
 	tuple.src.u3.ip = inet->rcv_saddr;
 	tuple.src.u.tcp.port = inet->sport;
 	tuple.dst.u3.ip = inet->daddr;

net/netfilter/nf_conntrack_core.c

···
 		const struct nf_conntrack_l3proto *l3proto,
 		const struct nf_conntrack_l4proto *l4proto)
 {
-	NF_CT_TUPLE_U_BLANK(tuple);
+	memset(tuple, 0, sizeof(*tuple));
 
 	tuple->src.l3num = l3num;
 	if (l3proto->pkt_to_tuple(skb, nhoff, tuple) == 0)
···
 		   const struct nf_conntrack_l3proto *l3proto,
 		   const struct nf_conntrack_l4proto *l4proto)
 {
-	NF_CT_TUPLE_U_BLANK(inverse);
+	memset(inverse, 0, sizeof(*inverse));
 
 	inverse->src.l3num = orig->src.l3num;
 	if (l3proto->invert_tuple(inverse, orig) == 0)