netfilter: nft_masq: fix uninitialized range in nft_masq_{ipv4, ipv6}_eval

When transferring from the original range in nf_nat_masquerade_{ipv4,ipv6}()
we copy over values from stack in from min_proto/max_proto due to uninitialized
range variable in both, nft_masq_{ipv4,ipv6}_eval. As we only initialize
flags at this time from nft_masq struct, just zero out the rest.

Fixes: 9ba1f726 ("netfilter: nf_tables: add new nft_masq expression")
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Acked-by: NArturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/ipv4/netfilter/nft_masq_ipv4.c

@@ -24,6 +24,7 @@ static void nft_masq_ipv4_eval(const struct nft_expr *expr,
 	struct nf_nat_range range;
 	unsigned int verdict;
 
+	memset(&range, 0, sizeof(range));
 	range.flags = priv->flags;
 
 	verdict = nf_nat_masquerade_ipv4(pkt->skb, pkt->ops->hooknum,

net/ipv6/netfilter/nft_masq_ipv6.c

@@ -25,6 +25,7 @@ static void nft_masq_ipv6_eval(const struct nft_expr *expr,
 	struct nf_nat_range range;
 	unsigned int verdict;
 
+	memset(&range, 0, sizeof(range));
 	range.flags = priv->flags;
 
 	verdict = nf_nat_masquerade_ipv6(pkt->skb, &range, pkt->out);