mld_{query | report}_work() processes queued events.
If there are too many events in the queue, it re-queue a work.
And then, it returns without in6_dev_put().
But if queuing is failed, it should call in6_dev_put(), but it doesn't.
So, a reference count leak would occur.
THREAD0 THREAD1
mld_report_work()
spin_lock_bh()
if (!mod_delayed_work())
in6_dev_hold();
spin_unlock_bh()
spin_lock_bh()
schedule_delayed_work()
spin_unlock_bh()
Script to reproduce(by Hangbin Liu):
ip netns add ns1
ip netns add ns2
ip netns exec ns1 sysctl -w net.ipv6.conf.all.force_mld_version=1
ip netns exec ns2 sysctl -w net.ipv6.conf.all.force_mld_version=1
ip -n ns1 link add veth0 type veth peer name veth0 netns ns2
ip -n ns1 link set veth0 up
ip -n ns2 link set veth0 up
for i in `seq 50`; do
for j in `seq 100`; do
ip -n ns1 addr add 2021:${i}::${j}/64 dev veth0
ip -n ns2 addr add 2022:${i}::${j}/64 dev veth0
done
done
modprobe -r veth
ip -a netns del
splat looks like:
unregister_netdevice: waiting for veth0 to become free. Usage count = 2
leaked reference.
ipv6_add_dev+0x324/0xec0
addrconf_notify+0x481/0xd10
raw_notifier_call_chain+0xe3/0x120
call_netdevice_notifiers+0x106/0x160
register_netdevice+0x114c/0x16b0
veth_newlink+0x48b/0xa50 [veth]
rtnl_newlink+0x11a2/0x1a40
rtnetlink_rcv_msg+0x63f/0xc00
netlink_rcv_skb+0x1df/0x3e0
netlink_unicast+0x5de/0x850
netlink_sendmsg+0x6c9/0xa90
____sys_sendmsg+0x76a/0x780
__sys_sendmsg+0x27c/0x340
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Tested-by: Hangbin Liu <liuhangbin@gmail.com>
Fixes: f185de28d9 ("mld: add new workqueues for process mld events")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
3e7d18b9dc