ipv4: fix nexthop attlen check in fib_nh_match

fib_nh_match does not match nexthops correctly. Example:

ip route add 172.16.10/24 nexthop via 192.168.122.12 dev eth0 \
                          nexthop via 192.168.122.13 dev eth0
ip route del 172.16.10/24 nexthop via 192.168.122.14 dev eth0 \
                          nexthop via 192.168.122.15 dev eth0

Del command is successful and route is removed. After this patch
applied, the route is correctly matched and result is:
RTNETLINK answers: No such process

Please consider this for stable trees as well.

Fixes: 4e902c57417c4 ("[IPv4]: FIB configuration using struct fib_config")
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 5b6efb3d2308b0b40b22da7274ad611c4f3d0158..f99f41bd15b83072d7a67cd452a29ce550e0593e 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -537,7 +537,7 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
                        return 1;
 
                attrlen = rtnh_attrlen(rtnh);
-               if (attrlen < 0) {
+               if (attrlen > 0) {
                        struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 
                        nla = nla_find(attrs, attrlen, RTA_GATEWAY);