Patch "net: ipv6: fix regression of no RTM_DELADDR sent after DAD failure" has been added to the 4.13-stable tree

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

net: ipv6: fix regression of no RTM_DELADDR sent after DAD failure

to the 4.13-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:
net-ipv6-fix-regression-of-no-rtm_deladdr-sent-after-dad-failure.patch
and it can be found in the queue-4.13 subdirectory.

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

From: Mike Manning <[email protected]>
Date: Mon, 4 Sep 2017 15:52:55 +0100
Subject: net: ipv6: fix regression of no RTM_DELADDR sent after DAD failure

From: Mike Manning <[email protected]>

[ Upstream commit 6819a14ecbe2e089e5c5bb74edecafdde2028a00 ]

Commit f784ad3d79e5 ("ipv6: do not send RTM_DELADDR for tentative addresses") incorrectly assumes that no RTM_NEWADDR are sent for addresses in tentative state, as this does happen for the standard IPv6 use-case of DAD failure, see the call to ipv6_ifa_notify() in addconf_dad_stop(). So as a result of this change, no RTM_DELADDR is sent after DAD failure for a link-local when strict DAD (accept_dad=2) is configured, or on the next admin down in other cases. The absence of this notification breaks backwards compatibility and causes problems after DAD failure if this notification was being relied on. The solution is to allow RTM_DELADDR to still be sent after DAD failure.

---
 net/ipv6/addrconf.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

@@ -4982,9 +4982,10 @@ static void inet6_ifa_notify(int event,
 
 	/* Don't send DELADDR notification for TENTATIVE address,
 	 * since NEWADDR notification is sent only after removing
-	 * TENTATIVE flag.
+	 * TENTATIVE flag, if DAD has not failed.
 	 */
-	if (ifa->flags & IFA_F_TENTATIVE && event == RTM_DELADDR)
+	if (ifa->flags & IFA_F_TENTATIVE && !(ifa->flags & IFA_F_DADFAILED) &&
+	    event == RTM_DELADDR)
 		return;
 
 	skb = nlmsg_new(inet6_ifaddr_msgsize(), GFP_ATOMIC);

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

queue-4.13/net-ipv6-fix-regression-of-no-rtm_deladdr-sent-after-dad-failure.patch