net: ipv4: fix table id in getroute response

[ Upstream commit 8a430ed50bb1b19ca14a46661f3b1b35f2fb5c39 ]

rtm_table is an 8-bit field while table ids are allowed up to u32. Commit
709772e ("net: Fix routing tables with id > 255 for legacy software")
added the preference to set rtm_table in dumps to RT_TABLE_COMPAT if the
table id is > 255. The table id returned on get route requests should do
the same.

Fixes: c36ba66 ("net: Allow user to get table id from route lookup")
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: David Ahern

net/ipv4/route.c

@@ -2430,7 +2430,7 @@ static int rt_fill_info(struct net *net,  __be32 dst, __be32 src, u32 table_id,
 	r->rtm_dst_len	= 32;
 	r->rtm_src_len	= 0;
 	r->rtm_tos	= fl4->flowi4_tos;
-	r->rtm_table	= table_id;
+	r->rtm_table	= table_id < 256 ? table_id : RT_TABLE_COMPAT;
 	if (nla_put_u32(skb, RTA_TABLE, table_id))
 		goto nla_put_failure;
 	r->rtm_type	= rt->rt_type;