net: fib_rules: Correctly set table field when table number exceeds 8 bits

BugLink: https://bugs.launchpad.net/bugs/1868628

[ Upstream commit 540e585a ]

In 709772e6, RT_TABLE_COMPAT was added to
allow legacy software to deal with routing table numbers >= 256, but the
same change to FIB rule queries was overlooked.
Signed-off-by: Jethro Beekman <jethro@fortanix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

net/core/fib_rules.c

@@ -570,7 +570,7 @@ static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 
 	frh = nlmsg_data(nlh);
 	frh->family = ops->family;
-	frh->table = rule->table;
+	frh->table = rule->table < 256 ? rule->table : RT_TABLE_COMPAT;
 	if (nla_put_u32(skb, FRA_TABLE, rule->table))
 		goto nla_put_failure;
 	if (nla_put_u32(skb, FRA_SUPPRESS_PREFIXLEN, rule->suppress_prefixlen))