Subject: INFO: task hung in ctrl_getfamily

From: syzbot <[email-masked]>
Date: Tue, 11 Dec 2018 02:03:03 -0800

Hello,

syzbot found the following crash on:

HEAD commit:    40e020c129cf Linux 4.20-rc6
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=146ff5a3400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c8970c89a0efbb23
dashboard link: https://syzkaller.appspot.com/bug?extid=36edb5cac286af8e3385
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14f04d6d400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]

IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0
INFO: task syz-executor0:6314 blocked for more than 140 seconds.
       Not tainted 4.20.0-rc6+ #370
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D21448  6314   6054 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:2831 [inline]
  __schedule+0x8cf/0x21d0 kernel/sched/core.c:3472
  schedule+0xfe/0x460 kernel/sched/core.c:3516
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3574
  __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
  __mutex_lock+0xaff/0x16f0 kernel/locking/mutex.c:1072
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
  genl_lock net/netlink/genetlink.c:33 [inline]
  ctrl_getfamily+0x313/0x420 net/netlink/genetlink.c:873
  genl_family_rcv_msg+0x8a7/0x11a0 net/netlink/genetlink.c:601
  genl_rcv_msg+0xc6/0x168 net/netlink/genetlink.c:626
  netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477
  genl_rcv+0x28/0x40 net/netlink/genetlink.c:637
  netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
  netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
  netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg+0xd5/0x120 net/socket.c:631
  ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
  __sys_sendmsg+0x11d/0x280 net/socket.c:2154
  __do_sys_sendmsg net/socket.c:2163 [inline]
  __se_sys_sendmsg net/socket.c:2161 [inline]
  __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x411231
Code: 01 4c 89 54 24 28 e9 6f fa ff ff 49 8b 7c 24 70 8b 35 43 c4 24 00 ff  
15 ed 83 24 00 85 c0 0f 85 b3 fe ff ff 49 8b 7c 24 70 be <20> 13 41 00 ff  
15 dd 83 24 00 85 c0 0f 85 9b fe ff ff 49 8b 7c 24
RSP: 002b:00007fc4f0d7f9c0 EFLAGS: 00000293 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000411231
RDX: 0000000000000000 RSI: 00007fc4f0d7fa00 RDI: 0000000000000006
RBP: 0000000000000006 R08: 00007fc4f0d7f9d0 R09: 000000000072bf00
R10: 0000000000000005 R11: 0000000000000293 R12: 00007fc4f0d7fa40
R13: 00000000004cc470 R14: 00000000004d9950 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1019:
  #0: 0000000018acca81 (rcu_read_lock){....}, at:  
debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4379
1 lock held by rsyslogd/5919:
  #0: 00000000a301519f (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200  
fs/file.c:766
2 locks held by getty/6010:
  #0: 000000008d1ae09f (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 000000001356f661 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/6011:
  #0: 00000000c1ee7f5a (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 0000000053bcc6b4 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/6012:
  #0: 000000003937906c (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 000000005503206b (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/6013:
  #0: 00000000e7a22898 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000a0e9cef1 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/6014:
  #0: 000000002666d591 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000a02c8c57 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/6015:
  #0: 00000000bc3e2096 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000c9a713a6 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/6016:
  #0: 00000000076cf5e3 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000dd03af83 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by syz-executor0/6314:
  #0: 00000000cf395c86 (cb_lock){++++}, at: ctrl_getfamily+0x305/0x420  
net/netlink/genetlink.c:872
  #1: 000000004b0549ce (genl_mutex){+.+.}, at: genl_lock  
net/netlink/genetlink.c:33 [inline]
  #1: 000000004b0549ce (genl_mutex){+.+.}, at: ctrl_getfamily+0x313/0x420  
net/netlink/genetlink.c:873
3 locks held by syz-executor0/6317:

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1019 Comm: khungtaskd Not tainted 4.20.0-rc6+ #370
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x244/0x39d lib/dump_stack.c:113
  nmi_cpu_backtrace.cold.2+0x5c/0xa1 lib/nmi_backtrace.c:101
  nmi_trigger_cpumask_backtrace+0x1e8/0x22a lib/nmi_backtrace.c:62
  arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
  trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
  check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
  watchdog+0xb51/0x1060 kernel/hung_task.c:289
  kthread+0x35a/0x440 kernel/kthread.c:246
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.855  
msecs
NMI backtrace for cpu 1
CPU: 1 PID: 6317 Comm: syz-executor0 Not tainted 4.20.0-rc6+ #370
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs+0x4e/0x170 kernel/rcu/tree.c:289
Code: 48 c1 eb 03 48 83 ec 68 48 c7 45 80 b3 8a b5 41 4a 8d 04 33 48 c7 45  
88 80 96 11 89 48 c7 45 90 90 6a 6a 81 c7 00 f1 f1 f1 f1 <c7> 40 04 04 f2  
f2 f2 65 48 8b 04 25 28 00 00 00 48 89 45 d8 31 c0
RSP: 0018:ffff8881bab0e810 EFLAGS: 00000282
RAX: ffffed1037561d03 RBX: 1ffff11037561d03 RCX: ffffffff87a2367c
RDX: 0000000000000000 RSI: ffffffff87a2368a RDI: ffff8881bb77a8fc
RBP: ffff8881bab0e898 R08: ffff8881bb77a080 R09: ffffed103b5e5b5f
R10: ffffed103b5e5b5f R11: ffff8881daf2dafb R12: 000000000002da40
R13: ffff8881bab0e878 R14: dffffc0000000000 R15: ffff8881b6cc9b80
FS:  00007fc4f0d5f700(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000001b318c000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  rcu_is_watching+0x10/0x30 kernel/rcu/tree.c:906
  rcu_read_lock_held+0x87/0xc0 kernel/rcu/update.c:277
  __rhashtable_lookup include/linux/rhashtable.h:478 [inline]
  rhashtable_lookup include/linux/rhashtable.h:516 [inline]
  rhashtable_lookup_fast include/linux/rhashtable.h:542 [inline]
  tipc_sk_lookup+0xa4f/0xff0 net/tipc/socket.c:2746
  tipc_nl_publ_dump+0x22d/0xf93 net/tipc/socket.c:3550
  __tipc_nl_compat_dumpit.isra.11+0x25d/0xb60 net/tipc/netlink_compat.c:196
  tipc_nl_compat_publ_dump net/tipc/netlink_compat.c:925 [inline]
  tipc_nl_compat_sk_dump+0x88e/0xc50 net/tipc/netlink_compat.c:973
  __tipc_nl_compat_dumpit.isra.11+0x389/0xb60 net/tipc/netlink_compat.c:205
  tipc_nl_compat_dumpit+0x1f4/0x440 net/tipc/netlink_compat.c:270
  tipc_nl_compat_handle net/tipc/netlink_compat.c:1147 [inline]
  tipc_nl_compat_recv+0x12b3/0x19a0 net/tipc/netlink_compat.c:1210
  genl_family_rcv_msg+0x8a7/0x11a0 net/netlink/genetlink.c:601
  genl_rcv_msg+0xc6/0x168 net/netlink/genetlink.c:626
  netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477
  genl_rcv+0x28/0x40 net/netlink/genetlink.c:637
  netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
  netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
  netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg+0xd5/0x120 net/socket.c:631
  ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
  __sys_sendmsg+0x11d/0x280 net/socket.c:2154
  __do_sys_sendmsg net/socket.c:2163 [inline]
  __se_sys_sendmsg net/socket.c:2161 [inline]
  __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457659
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc4f0d5ec78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457659
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000005
RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc4f0d5f6d4
R13: 00000000004c4171 R14: 00000000004d7058 R15: 00000000ffffffff

---
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