Patch "ipv6: avoid dad-failures for addresses with NODAD" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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 <stable@vger.kernel.org> know about it.


>From foo@baz Mon Apr  9 17:09:24 CEST 2018
From: Mahesh Bandewar <maheshb@google.com>
Date: Fri, 12 May 2017 17:03:39 -0700
Subject: ipv6: avoid dad-failures for addresses with NODAD

From: Mahesh Bandewar <maheshb@google.com>


[ 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.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv6/addrconf.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -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 maheshb@google.com 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