Messages in this thread | | | Subject | Re: WARNING in kcm_exit_net (3) | From | Kirill Tkhai <> | Date | Thu, 31 May 2018 12:58:56 +0300 |
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On 31.05.2018 11:16, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: d60d61f36b8f Merge branch 'for-linus' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=101bb52f800000 > kernel config: https://syzkaller.appspot.com/x/.config?x=968b0b23c7854c0b > dashboard link: https://syzkaller.appspot.com/bug?extid=5f1a04e374a635efc426 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13b9ed2f800000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+5f1a04e374a635efc426@syzkaller.appspotmail.com > > IPVS: ftp: loaded support on port[0] = 21 > IPVS: ftp: loaded support on port[0] = 21 > IPVS: ftp: loaded support on port[0] = 21 > IPVS: ftp: loaded support on port[0] = 21 > IPVS: ftp: loaded support on port[0] = 21 > WARNING: CPU: 0 PID: 6 at net/kcm/kcmsock.c:2023 kcm_exit_net+0x392/0x3e0 net/kcm/kcmsock.c:2023
Hm, there is allocated a kernel socket in kcm_clone(). It does not get net counter and it seems kcm_done_work() may complete after kcm_exit_net() is completed. So, it looks like we have to flush work queue in kcm_exit_net().
> Kernel panic - not syncing: panic_on_warn set ... > > CPU: 0 PID: 6 Comm: kworker/u4:0 Not tainted 4.17.0-rc7+ #75 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: netns cleanup_net > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x1b9/0x294 lib/dump_stack.c:113 > panic+0x22f/0x4de kernel/panic.c:184 > __warn.cold.8+0x163/0x1b3 kernel/panic.c:536 > report_bug+0x252/0x2d0 lib/bug.c:186 > fixup_bug arch/x86/kernel/traps.c:178 [inline] > do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296 > do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315 > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992 > RIP: 0010:kcm_exit_net+0x392/0x3e0 net/kcm/kcmsock.c:2023 > RSP: 0018:ffff8801d9a97430 EFLAGS: 00010293 > RAX: ffff8801d9a88180 RBX: 1ffff1003b352e86 RCX: 1ffff1003b351135 > RDX: 0000000000000000 RSI: ffffffff86d56942 RDI: 0000000000000286 > RBP: ffff8801d9a974f8 R08: 1ffff1003b352e67 R09: ffffed003b5c46d2 > R10: 0000000000000003 R11: 0000000000000003 R12: 1ffff1003b352e8a > R13: ffff8801d9a974d0 R14: ffff8801d96763d0 R15: ffff8801c51d0e00 > ops_exit_list.isra.7+0xb0/0x160 net/core/net_namespace.c:152 > cleanup_net+0x51d/0xb20 net/core/net_namespace.c:523 > process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 > worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 > kthread+0x345/0x410 kernel/kthread.c:240 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 > Dumping ftrace buffer: > (ftrace buffer empty) > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches
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