Patch "ipv6: avoid dad-failures for addresses with NODAD" 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

ipv6: avoid dad-failures for addresses with NODAD

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:
ipv6-avoid-dad-failures-for-addresses-with-nodad.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: Mahesh Bandewar <[email protected]>
Date: Fri, 12 May 2017 17:03:39 -0700
Subject: ipv6: avoid dad-failures for addresses with NODAD

From: Mahesh Bandewar <[email protected]>

[ Upstream commit 66eb9f86e50547ec2a8ff7a75997066a74ef584b ]

Every address gets added with TENTATIVE flag even for the addresses with IFA_F_NODAD flag and dad-work is scheduled for them. During this DAD process we realize it's an address with NODAD and complete the process without sending any probe. However the TENTATIVE flags stays on the address for sometime enough to cause misinterpretation when we receive a NS. While processing NS, if the address has TENTATIVE flag, we mark it DADFAILED and endup with an address that was originally configured as NODAD with DADFAILED.

We can't avoid scheduling dad_work for addresses with NODAD but we can avoid adding TENTATIVE flag to avoid this racy situation.

---
 net/ipv6/addrconf.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

@@ -988,7 +988,10 @@ ipv6_add_addr(struct inet6_dev *idev, co
 	INIT_HLIST_NODE(&ifa->addr_lst);
 	ifa->scope = scope;
 	ifa->prefix_len = pfxlen;
-	ifa->flags = flags | IFA_F_TENTATIVE;
+	ifa->flags = flags;
+	/* No need to add the TENTATIVE flag for addresses with NODAD */
+	if (!(flags & IFA_F_NODAD))
+		ifa->flags |= IFA_F_TENTATIVE;
 	ifa->valid_lft = valid_lft;
 	ifa->prefered_lft = prefered_lft;
 	ifa->cstamp = ifa->tstamp = jiffies;

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

queue-4.9/bonding-don-t-update-slave-link-until-ready-to-commit.patch queue-4.9/ipv6-avoid-dad-failures-for-addresses-with-nodad.patch