From: Wei Yongjun Date: Mon, 5 Sep 2016 08:06:31 +0000 (+0800) Subject: ipv6: addrconf: fix dev refcont leak when DAD failed X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=751eb6b6042a596b0080967c1a529a9fe98dac1d;p=openwrt%2Fstaging%2Fblogic.git ipv6: addrconf: fix dev refcont leak when DAD failed 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@vger.kernel.org Fixes: c15b1ccadb32 ("ipv6: move DAD and addrconf_verify processing to workqueue") Signed-off-by: Wei Yongjun Signed-off-by: David S. Miller --- diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index bdf368eff5ab..2f1f5d439788 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -1948,6 +1948,7 @@ errdad: spin_unlock_bh(&ifp->lock); addrconf_mod_dad_work(ifp, 0); + in6_ifa_put(ifp); } /* Join to solicited addr multicast group. @@ -3857,6 +3858,7 @@ static void addrconf_dad_work(struct work_struct *w) addrconf_dad_begin(ifp); goto out; } else if (action == DAD_ABORT) { + in6_ifa_hold(ifp); addrconf_dad_stop(ifp, 1); if (disable_ipv6) addrconf_ifdown(idev->dev, 0);