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: 9ba1f726bec09 ("netfilter: nf_tables: add new nft_masq expression")
Signed-off-by: Daniel Borkmann <[e-mail]>
Acked-by: Arturo Borrero Gonzalez <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/ipv4/netfilter/nft_masq_ipv4.c

···
 	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

···
 	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);