Subject: netfilter: active obj WARN when cleaning up

From: Sasha Levin <[email-masked]>
Date: Sat, 07 Sep 2013 09:10:13 -0400

Hi all,

While fuzzing with trinity inside a KVM tools guest, running latest -next kernel, I've
stumbled on the following:

[  418.311956] ------------[ cut here ]------------
[  418.312449] WARNING: CPU: 6 PID: 4178 at lib/debugobjects.c:260 debug_print_object+0x8d/0xb0()
[  418.313243] ODEBUG: free active (active state 0) object type: timer_list hint: 
delayed_work_timer_fn+0x0/0x20
[  418.314038] Modules linked in:
[  418.314038] CPU: 6 PID: 4178 Comm: kworker/u16:2 Tainted: G        W 
3.11.0-next-20130906-sasha #3984
[  418.314038] Workqueue: netns cleanup_net
[  418.314038]  0000000000000104 ffff880410371a58 ffffffff841b7815 0000000000000104
[  418.314038]  ffff880410371aa8 ffff880410371a98 ffffffff8112540c ffff880410371a78
[  418.314038]  ffffffff853ea0ab ffff8800bdc68b80 ffffffff85a65c00 ffffffff87676658
[  418.314038] Call Trace:
[  418.314038]  [<ffffffff841b7815>] dump_stack+0x52/0x87
[  418.320315]  [<ffffffff8112540c>] warn_slowpath_common+0x8c/0xc0
[  418.321040]  [<ffffffff811254f6>] warn_slowpath_fmt+0x46/0x50
[  418.321101]  [<ffffffff81a60ded>] debug_print_object+0x8d/0xb0
[  418.321101]  [<ffffffff811444e0>] ? __queue_work+0x390/0x390
[  418.321101]  [<ffffffff81a61605>] __debug_check_no_obj_freed+0xa5/0x220
[  418.321101]  [<ffffffff81249e76>] ? kmem_cache_destroy+0x86/0xe0
[  418.321101]  [<ffffffff81a61795>] debug_check_no_obj_freed+0x15/0x20
[  418.321101]  [<ffffffff812874d7>] kmem_cache_free+0x197/0x340
[  418.321101]  [<ffffffff81249e76>] kmem_cache_destroy+0x86/0xe0
[  418.321101]  [<ffffffff83d5d681>] nf_conntrack_cleanup_net_list+0x131/0x170
[  418.321101]  [<ffffffff83d5ec5d>] nf_conntrack_pernet_exit+0x5d/0x70
[  418.321101]  [<ffffffff83cda1ce>] ops_exit_list+0x5e/0x70
[  418.321101]  [<ffffffff83cda80b>] cleanup_net+0xfb/0x1c0
[  418.321101]  [<ffffffff81145c28>] process_one_work+0x338/0x550
[  418.321101]  [<ffffffff81145b50>] ? process_one_work+0x260/0x550
[  418.321883]  [<ffffffff81147605>] worker_thread+0x215/0x350
[  418.321883]  [<ffffffff811473f0>] ? manage_workers+0x180/0x180
[  418.321883]  [<ffffffff81150887>] kthread+0xe7/0xf0
[  418.321883]  [<ffffffff811507a0>] ? __init_kthread_worker+0x70/0x70
[  418.321883]  [<ffffffff841c7a2c>] ret_from_fork+0x7c/0xb0
[  418.321883]  [<ffffffff811507a0>] ? __init_kthread_worker+0x70/0x70
[  418.321883] ---[ end trace c974221542b61d0d ]---

Thanks,
Sasha