netfilter: fix hardcoded size assumptions

get_random_bytes() is sometimes called with a hard coded size assumption
of an integer. This could not be true for next centuries. This patch
replace it with a compile time statement.
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/netfilter/nf_conntrack_core.c

@@ -472,7 +472,8 @@ struct nf_conn *nf_conntrack_alloc(struct net *net,
 	struct nf_conn *ct;
 
 	if (unlikely(!nf_conntrack_hash_rnd_initted)) {
-		get_random_bytes(&nf_conntrack_hash_rnd, 4);
+		get_random_bytes(&nf_conntrack_hash_rnd,
+				sizeof(nf_conntrack_hash_rnd));
 		nf_conntrack_hash_rnd_initted = 1;
 	}
 
@@ -1103,7 +1104,7 @@ int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp)
 
 	/* We have to rehahs for the new table anyway, so we also can
 	 * use a newrandom seed */
-	get_random_bytes(&rnd, 4);
+	get_random_bytes(&rnd, sizeof(rnd));
 
 	/* Lookups in the old hash might happen in parallel, which means we
 	 * might get false negatives during connection lookup. New connections

net/netfilter/nf_conntrack_expect.c

@@ -72,7 +72,8 @@ static unsigned int nf_ct_expect_dst_hash(const struct nf_conntrack_tuple *tuple
 	unsigned int hash;
 
 	if (unlikely(!nf_ct_expect_hash_rnd_initted)) {
-		get_random_bytes(&nf_ct_expect_hash_rnd, 4);
+		get_random_bytes(&nf_ct_expect_hash_rnd,
+				 sizeof(nf_ct_expect_hash_rnd));
 		nf_ct_expect_hash_rnd_initted = 1;
 	}
 

net/netfilter/xt_hashlimit.c

@@ -149,7 +149,7 @@ dsthash_alloc_init(struct xt_hashlimit_htable *ht,
 	/* initialize hash with random val at the time we allocate
 	 * the first hashtable entry */
 	if (!ht->rnd_initialized) {
-		get_random_bytes(&ht->rnd, 4);
+		get_random_bytes(&ht->rnd, sizeof(ht->rnd));
 		ht->rnd_initialized = 1;
 	}