diff options
| author | Xin Long <lucien.xin@gmail.com> | 2017-06-15 16:33:58 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-06-15 11:26:16 -0400 |
| commit | f8a894b218138888542a5058d0e902378fd0d4ec (patch) | |
| tree | 12a20e086cb52fed4037eaec3c40a0718d59a4ac /net | |
| parent | a090bd4ff8387c409732a8e059fbf264ea0bdd56 (diff) | |
ipv6: fix calling in6_ifa_hold incorrectly for dad work
Now when starting the dad work in addrconf_mod_dad_work, if the dad work
is idle and queued, it needs to hold ifa.
The problem is there's one gap in [1], during which if the pending dad work
is removed elsewhere. It will miss to hold ifa, but the dad word is still
idea and queue.
if (!delayed_work_pending(&ifp->dad_work))
in6_ifa_hold(ifp);
<--------------[1]
mod_delayed_work(addrconf_wq, &ifp->dad_work, delay);
An use-after-free issue can be caused by this.
Chen Wei found this issue when WARN_ON(!hlist_unhashed(&ifp->addr_lst)) in
net6_ifa_finish_destroy was hit because of it.
As Hannes' suggestion, this patch is to fix it by holding ifa first in
addrconf_mod_dad_work, then calling mod_delayed_work and putting ifa if
the dad_work is already in queue.
Note that this patch did not choose to fix it with:
if (!mod_delayed_work(delay))
in6_ifa_hold(ifp);
As with it, when delay == 0, dad_work would be scheduled immediately, all
addrconf_mod_dad_work(0) callings had to be moved under ifp->lock.
Reported-by: Wei Chen <weichen@redhat.com>
Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv6/addrconf.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 6a4fb1e629fb..686c92375e81 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -332,9 +332,9 @@ static void addrconf_mod_rs_timer(struct inet6_dev *idev, static void addrconf_mod_dad_work(struct inet6_ifaddr *ifp, unsigned long delay) { - if (!delayed_work_pending(&ifp->dad_work)) - in6_ifa_hold(ifp); - mod_delayed_work(addrconf_wq, &ifp->dad_work, delay); + in6_ifa_hold(ifp); + if (mod_delayed_work(addrconf_wq, &ifp->dad_work, delay)) + in6_ifa_put(ifp); } static int snmp6_alloc_dev(struct inet6_dev *idev) |