[PATCH 4.9 122/148] route: also update fnhe_genid when updating a route cache

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Xin Long <lucien.xin@xxxxxxxxx>


[ Upstream commit cebe84c6190d741045a322f5343f717139993c08 ]

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@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv4/route.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -630,9 +630,12 @@ static void update_or_create_fnhe(struct
 	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);
 
@@ -655,6 +658,8 @@ static void update_or_create_fnhe(struct
 	}
 
 	if (fnhe) {
+		if (fnhe->fnhe_genid != genid)
+			fnhe->fnhe_genid = genid;
 		if (gw)
 			fnhe->fnhe_gw = gw;
 		if (pmtu) {
@@ -679,7 +684,7 @@ static void update_or_create_fnhe(struct
 			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;