nexthops: Add selftests for cleanup of known bad route add

Test cleanup path for routes usinig nexthop objects before the
reference is taken on the nexthop. Specifically, bad metric for
ipv4 and ipv6 and source routing for ipv6.

Selftests that correspond to the recent bug fix:
    821bbf79 ("ipv6: Fix KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions")
Signed-off-by: NDavid Ahern <dsahern@kernel.org>
Cc: Coco Li <lixiaoyan@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/net/fib_nexthops.sh

@@ -925,6 +925,14 @@ ipv6_fcnal_runtime()
 	run_cmd "$IP nexthop add id 86 via 2001:db8:91::2 dev veth1"
 	run_cmd "$IP ro add 2001:db8:101::1/128 nhid 81"
 
+	# route can not use prefsrc with nexthops
+	run_cmd "$IP ro add 2001:db8:101::2/128 nhid 86 from 2001:db8:91::1"
+	log_test $? 2 "IPv6 route can not use src routing with external nexthop"
+
+	# check cleanup path on invalid metric
+	run_cmd "$IP ro add 2001:db8:101::2/128 nhid 86 congctl lock foo"
+	log_test $? 2 "IPv6 route with invalid metric"
+
 	# rpfilter and default route
 	$IP nexthop flush >/dev/null 2>&1
 	run_cmd "ip netns exec me ip6tables -t mangle -I PREROUTING 1 -m rpfilter --invert -j DROP"
@@ -1366,6 +1374,10 @@ ipv4_fcnal_runtime()
 	run_cmd "$IP nexthop replace id 22 via 172.16.2.2 dev veth3"
 	log_test $? 2 "Nexthop replace with invalid scope for existing route"
 
+	# check cleanup path on invalid metric
+	run_cmd "$IP ro add 172.16.101.2/32 nhid 22 congctl lock foo"
+	log_test $? 2 "IPv4 route with invalid metric"
+
 	#
 	# add route with nexthop and check traffic
 	#