route: also update fnhe_genid when updating a route cache

Now when ip route flush cache and it turn out all fnhe_genid != genid.
If a redirect/pmtu icmp packet comes and the old fnhe is found and all
it's members but fnhe_genid will be updated.

Then next time when it looks up route and tries to rebind this fnhe to
the new dst, the fnhe will be flushed due to fnhe_genid != genid. It
causes this redirect/pmtu icmp packet acutally not to be applied.

This patch is to also reset fnhe_genid when updating a route cache.

Fixes: 5aad1de5ea2c ("ipv4: use separate genid for next hop exceptions")
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 11cf2fe43308..43b69af242e1 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -651,9 +651,12 @@ static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
         struct fnhe_hash_bucket *hash;
         struct fib_nh_exception *fnhe;
         struct rtable *rt;
+        u32 genid, hval;
         unsigned int i;
         int depth;
-        u32 hval = fnhe_hashfun(daddr);
+
+        genid = fnhe_genid(dev_net(nh->nh_dev));
+        hval = fnhe_hashfun(daddr);
 
         spin_lock_bh(&fnhe_lock);
 
@@ -676,6 +679,8 @@ static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
         }
 
         if (fnhe) {
+                if (fnhe->fnhe_genid != genid)
+                        fnhe->fnhe_genid = genid;
                 if (gw)
                         fnhe->fnhe_gw = gw;
                 if (pmtu)
@@ -699,7 +704,7 @@ static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
                         fnhe->fnhe_next = hash->chain;
                         rcu_assign_pointer(hash->chain, fnhe);
                 }
-                fnhe->fnhe_genid = fnhe_genid(dev_net(nh->nh_dev));
+                fnhe->fnhe_genid = genid;
                 fnhe->fnhe_daddr = daddr;
                 fnhe->fnhe_gw = gw;
                 fnhe->fnhe_pmtu = pmtu;