linux-kernel - [PATCH 4.9 026/108] ipv6: addrconf: fix generation of new temporary addresses

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Date:   Thu, 15 Jun 2017 19:52:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marcus Huewe <suse-tux@....de>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 026/108] ipv6: addrconf: fix generation of new temporary addresses

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

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

From: Marcus Huewe <suse-tux@....de>

[ Upstream commit a11a7f71cac209c7c9cca66eb506e1ebb033a3b3 ]

Under some circumstances it is possible that no new temporary addresses
will be generated.

For instance, addrconf_prefix_rcv_add_addr() indirectly calls
ipv6_create_tempaddr(), which creates a tentative temporary address and
starts dad. Next, addrconf_prefix_rcv_add_addr() indirectly calls
addrconf_verify_rtnl(). Now, assume that the previously created temporary
address has the least preferred lifetime among all existing addresses and
is still tentative (that is, dad is still running). Hence, the next run of
addrconf_verify_rtnl() is performed when the preferred lifetime of the
temporary address ends. If dad succeeds before the next run, the temporary
address becomes deprecated during the next run, but no new temporary
address is generated.

In order to fix this, schedule the next addrconf_verify_rtnl() run slightly
before the temporary address becomes deprecated, if dad succeeded.

Signed-off-by: Marcus Huewe <suse-tux@....de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv6/addrconf.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4004,6 +4004,12 @@ static void addrconf_dad_completed(struc

 	if (bump_id)
 		rt_genid_bump_ipv6(dev_net(dev));
+
+	/* Make sure that a new temporary address will be created
+	 * before this temporary address becomes deprecated.
+	 */
+	if (ifp->flags & IFA_F_TEMPORARY)
+		addrconf_verify_rtnl();
 }

 static void addrconf_dad_run(struct inet6_dev *idev)