This is a note to let you know that I've just added the patch titled ipv6: addrconf: fix dev refcont leak when DAD failed to the 4.7-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-addrconf-fix-dev-refcont-leak-when-dad-failed.patch and it can be found in the queue-4.7 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Sep 21 10:05:18 CEST 2016 From: Wei Yongjun <weiyongjun1@xxxxxxxxxx> Date: Mon, 5 Sep 2016 16:06:31 +0800 Subject: ipv6: addrconf: fix dev refcont leak when DAD failed From: Wei Yongjun <weiyongjun1@xxxxxxxxxx> [ Upstream commit 751eb6b6042a596b0080967c1a529a9fe98dac1d ] In general, when DAD detected IPv6 duplicate address, ifp->state will be set to INET6_IFADDR_STATE_ERRDAD and DAD is stopped by a delayed work, the call tree should be like this: ndisc_recv_ns -> addrconf_dad_failure <- missing ifp put -> addrconf_mod_dad_work -> schedule addrconf_dad_work() -> addrconf_dad_stop() <- missing ifp hold before call it addrconf_dad_failure() called with ifp refcont holding but not put. addrconf_dad_work() call addrconf_dad_stop() without extra holding refcount. This will not cause any issue normally. But the race between addrconf_dad_failure() and addrconf_dad_work() may cause ifp refcount leak and netdevice can not be unregister, dmesg show the following messages: IPv6: eth0: IPv6 duplicate address fe80::XX:XXXX:XXXX:XX detected! ... unregister_netdevice: waiting for eth0 to become free. Usage count = 1 Cc: stable@xxxxxxxxxxxxxxx Fixes: c15b1ccadb32 ("ipv6: move DAD and addrconf_verify processing to workqueue") Signed-off-by: Wei Yongjun <weiyongjun1@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv6/addrconf.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -1906,6 +1906,7 @@ errdad: spin_unlock_bh(&ifp->lock); addrconf_mod_dad_work(ifp, 0); + in6_ifa_put(ifp); } /* Join to solicited addr multicast group. @@ -3771,6 +3772,7 @@ static void addrconf_dad_work(struct wor addrconf_dad_begin(ifp); goto out; } else if (action == DAD_ABORT) { + in6_ifa_hold(ifp); addrconf_dad_stop(ifp, 1); goto out; } Patches currently in stable-queue which might be from weiyongjun1@xxxxxxxxxx are queue-4.7/ipv6-addrconf-fix-dev-refcont-leak-when-dad-failed.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html