Messages in this thread | | | From | Cong Wang <> | Date | Mon, 23 Mar 2020 10:48:20 -0700 | Subject | Re: WARNING: ODEBUG bug in tcindex_destroy_work (3) |
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On Sat, Mar 21, 2020 at 3:19 AM Thomas Gleixner <tglx@linutronix.de> wrote: > > syzbot <syzbot+46f513c3033d592409d2@syzkaller.appspotmail.com> writes: > > syzbot has found a reproducer for the following crash on: > > > > HEAD commit: 74522e7b net: sched: set the hw_stats_type in pedit loop > > git tree: net-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=14c85173e00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=b5acf5ac38a50651 > > dashboard link: https://syzkaller.appspot.com/bug?extid=46f513c3033d592409d2 > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17bfff65e00000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+46f513c3033d592409d2@syzkaller.appspotmail.com > > > > ------------[ cut here ]------------ > > ODEBUG: free active (active state 0) object type: work_struct hint: tcindex_destroy_rexts_work+0x0/0x20 net/sched/cls_tcindex.c:143 > ... > > __debug_check_no_obj_freed lib/debugobjects.c:967 [inline] > > debug_check_no_obj_freed+0x2e1/0x445 lib/debugobjects.c:998 > > kfree+0xf6/0x2b0 mm/slab.c:3756 > > tcindex_destroy_work+0x2e/0x70 net/sched/cls_tcindex.c:231 > > So this is: > > kfree(p->perfect); > > Looking at the place which queues that work: > > tcindex_destroy() > > if (p->perfect) { > if (tcf_exts_get_net(&r->exts)) > tcf_queue_work(&r-rwork, tcindex_destroy_rexts_work); > else > __tcindex_destroy_rexts(r) > } > > ..... > > tcf_queue_work(&p->rwork, tcindex_destroy_work); > > So obviously if tcindex_destroy_work() runs before > tcindex_destroy_rexts_work() then the above happens.
We use an ordered workqueue for tc filters, so these two works are executed in the same order as they are queued.
Thanks.
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