[patch net repost] ipv4: fix nexthop attlen check in fib_nh_match

[Jiri Pirko]

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 <***@resnulli.us>
Acked-by: Eric Dumazet <***@google.com>
---
reposted with example (it was missing for some reason in the original post)

net/ipv4/fib_semantics.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 5b6efb3..f99f41b 100644
--- 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);

[David Miller]

From: Jiri Pirko <***@resnulli.us>
Date: Mon, 13 Oct 2014 16:34:10 +0200

Post by Jiri Pirko
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
RTNETLINK answers: No such process
Please consider this for stable trees as well.
Fixes: 4e902c57417c4 ("[IPv4]: FIB configuration using struct fib_config")
---
reposted with example (it was missing for some reason in the original post)

Applied and queued up for -stable, thanks Jiri!