Patch "route: also update fnhe_genid when updating a route cache" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

route: also update fnhe_genid when updating a route cache

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
route-also-update-fnhe_genid-when-updating-a-route-cache.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Xin Long <[email protected]>
Date: Fri, 17 Nov 2017 14:27:18 +0800
Subject: route: also update fnhe_genid when updating a route cache

From: Xin Long <[email protected]>

[ 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.

---
 net/ipv4/route.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

@@ -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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/route-update-fnhe_expires-for-redirect-when-the-fnhe-exists.patch queue-4.9/route-also-update-fnhe_genid-when-updating-a-route-cache.patch queue-4.9/sctp-use-the-right-sk-after-waking-up-from-wait_buf-sleep.patch queue-4.9/sctp-do-not-free-asoc-when-it-is-already-dead-in-sctp_sendmsg.patch