netlink: 328 bytes leftover after parsing attributes in process `syz-executor2'.
netlink: 328 bytes leftover after parsing attributes in process `syz-executor2'.

======================================================
[ INFO: possible circular locking dependency detected ]
4.4.125-g38f41ec #21 Not tainted
-------------------------------------------------------
syz-executor1/12601 is trying to acquire lock:
 (_xmit_NETROM){+.-...}, at: [<ffffffff82ee5f7c>] spin_lock include/linux/spinlock.h:302 [inline]
 (_xmit_NETROM){+.-...}, at: [<ffffffff82ee5f7c>] __netif_tx_lock include/linux/netdevice.h:3299 [inline]
 (_xmit_NETROM){+.-...}, at: [<ffffffff82ee5f7c>] sch_direct_xmit+0x23c/0x760 net/sched/sch_generic.c:163

but task is already holding lock:
 (&(&q->lock)->rlock#2){+.-...}, at: [<ffffffff833a0627>] spin_lock include/linux/spinlock.h:302 [inline]
 (&(&q->lock)->rlock#2){+.-...}, at: [<ffffffff833a0627>] ipv6_frag_rcv+0x5e7/0x5020 net/ipv6/reassembly.c:560

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       [<ffffffff8123dcae>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
       [<ffffffff8377953e>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:112 [inline]
       [<ffffffff8377953e>] _raw_spin_lock_irqsave+0x4e/0x70 kernel/locking/spinlock.c:159
       [<ffffffff811bff3c>] try_to_wake_up+0x2c/0xf60 kernel/sched/core.c:1974
       [<ffffffff811c0f2e>] wake_up_q+0xbe/0x130 kernel/sched/core.c:582
       [<ffffffff83773d58>] __mutex_unlock_common_slowpath kernel/locking/mutex.c:754 [inline]
       [<ffffffff83773d58>] __mutex_unlock_slowpath+0x208/0x3b0 kernel/locking/mutex.c:765
       [<ffffffff83773f09>] mutex_unlock+0x9/0x10 kernel/locking/mutex.c:437
       [<ffffffff81f69512>] ptmx_open+0x102/0x320 drivers/tty/pty.c:770
       [<ffffffff8152a66b>] chrdev_open+0x22b/0x4c0 fs/char_dev.c:388
       [<ffffffff8151881b>] do_dentry_open+0x59b/0xba0 fs/open.c:749
       [<ffffffff8151c0e0>] vfs_open+0x110/0x210 fs/open.c:862
       [<ffffffff8154d373>] do_last fs/namei.c:3221 [inline]
       [<ffffffff8154d373>] path_openat+0x923/0x3940 fs/namei.c:3357
       [<ffffffff81553017>] do_filp_open+0x197/0x290 fs/namei.c:3392
       [<ffffffff8151cab9>] do_sys_open+0x369/0x660 fs/open.c:1038
       [<ffffffff8161d98d>] C_SYSC_openat fs/compat.c:1101 [inline]
       [<ffffffff8161d98d>] compat_SyS_openat+0x2d/0x40 fs/compat.c:1099
       [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
       [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
       [<ffffffff8377b2aa>] sysenter_flags_fixed+0xd/0x17

       [<ffffffff8123b00f>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
       [<ffffffff8123b00f>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
       [<ffffffff8123b00f>] validate_chain kernel/locking/lockdep.c:2144 [inline]
       [<ffffffff8123b00f>] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213
       [<ffffffff8123dcae>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
       [<ffffffff83778ad6>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
       [<ffffffff83778ad6>] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151
       [<ffffffff82ee5f7c>] spin_lock include/linux/spinlock.h:302 [inline]
       [<ffffffff82ee5f7c>] __netif_tx_lock include/linux/netdevice.h:3299 [inline]
       [<ffffffff82ee5f7c>] sch_direct_xmit+0x23c/0x760 net/sched/sch_generic.c:163
       [<ffffffff82e5f36e>] __dev_xmit_skb net/core/dev.c:2957 [inline]
       [<ffffffff82e5f36e>] __dev_queue_xmit+0x148e/0x1cc0 net/core/dev.c:3175
       [<ffffffff82e5fbb7>] dev_queue_xmit+0x17/0x20 net/core/dev.c:3241
       [<ffffffff82e7dd19>] neigh_resolve_output+0x469/0x770 net/core/neighbour.c:1312
       [<ffffffff83309520>] dst_neigh_output include/net/dst.h:461 [inline]
       [<ffffffff83309520>] ip6_finish_output2+0x990/0x1c60 net/ipv6/ip6_output.c:113
       [<ffffffff833129d6>] ip6_finish_output+0x2e6/0x750 net/ipv6/ip6_output.c:131
       [<ffffffff83312feb>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
       [<ffffffff83312feb>] ip6_output+0x1ab/0x520 net/ipv6/ip6_output.c:145
       [<ffffffff8336557a>] dst_output include/net/dst.h:498 [inline]
       [<ffffffff8336557a>] NF_HOOK_THRESH.constprop.24+0x11a/0x320 include/linux/netfilter.h:226
       [<ffffffff83366386>] NF_HOOK include/linux/netfilter.h:249 [inline]
       [<ffffffff83366386>] ndisc_send_skb+0x816/0xf80 net/ipv6/ndisc.c:471
       [<ffffffff8336a0d6>] ndisc_send_ns+0x2e6/0x720 net/ipv6/ndisc.c:595
       [<ffffffff8336a7b0>] ndisc_solicit+0x2a0/0x440 net/ipv6/ndisc.c:686
       [<ffffffff82e70e23>] neigh_probe+0xc3/0x100 net/core/neighbour.c:863
       [<ffffffff82e7b490>] __neigh_event_send+0x790/0xc40 net/core/neighbour.c:1019
       [<ffffffff82e7dd5a>] neigh_event_send include/net/neighbour.h:431 [inline]
       [<ffffffff82e7dd5a>] neigh_resolve_output+0x4aa/0x770 net/core/neighbour.c:1296
       [<ffffffff83309520>] dst_neigh_output include/net/dst.h:461 [inline]
       [<ffffffff83309520>] ip6_finish_output2+0x990/0x1c60 net/ipv6/ip6_output.c:113
       [<ffffffff833129d6>] ip6_finish_output+0x2e6/0x750 net/ipv6/ip6_output.c:131
       [<ffffffff83312feb>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
       [<ffffffff83312feb>] ip6_output+0x1ab/0x520 net/ipv6/ip6_output.c:145
       [<ffffffff834209d5>] dst_output include/net/dst.h:498 [inline]
       [<ffffffff834209d5>] ip6_local_out+0x95/0x170 net/ipv6/output_core.c:169
       [<ffffffff83315031>] ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1717
       [<ffffffff83315383>] ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1737
       [<ffffffff83385708>] icmpv6_push_pending_frames+0x338/0x530 net/ipv6/icmp.c:276
       [<ffffffff83386d6d>] icmp6_send+0x146d/0x1b70 net/ipv6/icmp.c:537
       [<ffffffff83388a29>] icmpv6_param_prob+0x29/0x40 net/ipv6/icmp.c:551
       [<ffffffff833a4050>] ip6_frag_queue net/ipv6/reassembly.c:263 [inline]
       [<ffffffff833a4050>] ipv6_frag_rcv+0x4010/0x5020 net/ipv6/reassembly.c:562
       [<ffffffff833160f9>] ip6_input_finish+0x329/0x1540 net/ipv6/ip6_input.c:248
       [<ffffffff83319276>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
       [<ffffffff83319276>] NF_HOOK include/linux/netfilter.h:249 [inline]
       [<ffffffff83319276>] ip6_input+0x106/0x200 net/ipv6/ip6_input.c:280
       [<ffffffff833158d8>] dst_input include/net/dst.h:504 [inline]
       [<ffffffff833158d8>] ip6_rcv_finish+0x138/0x630 net/ipv6/ip6_input.c:62
       [<ffffffff83318365>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
       [<ffffffff83318365>] NF_HOOK include/linux/netfilter.h:249 [inline]
       [<ffffffff83318365>] ipv6_rcv+0x1055/0x1e60 net/ipv6/ip6_input.c:186
       [<ffffffff82e51d99>] __netif_receive_skb_core+0xa59/0x28f0 net/core/dev.c:4019
       [<ffffffff82e53c8b>] __netif_receive_skb+0x5b/0x1c0 net/core/dev.c:4054
       [<ffffffff82e55cc3>] process_backlog+0x213/0x690 net/core/dev.c:4647
       [<ffffffff82e54fb3>] napi_poll net/core/dev.c:4885 [inline]
       [<ffffffff82e54fb3>] net_rx_action+0x373/0xe70 net/core/dev.c:4950
       [<ffffffff8377ce17>] __do_softirq+0x227/0xa38 kernel/softirq.c:273
       [<ffffffff8377abdc>] do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:929
       [<ffffffff8113bfb4>] do_softirq.part.17+0x54/0x60 kernel/softirq.c:317
       [<ffffffff8113dba9>] do_softirq+0x19/0x20 kernel/softirq.c:320
       [<ffffffff82e50616>] netif_rx_ni+0x166/0x3a0 net/core/dev.c:3653
       [<ffffffff826602d4>] tun_get_user+0xc74/0x2340 drivers/net/tun.c:1264
       [<ffffffff82661bb5>] tun_chr_write_iter+0xd5/0x190 drivers/net/tun.c:1283
       [<ffffffff8151e9f8>] do_iter_readv_writev+0x138/0x1e0 fs/read_write.c:664
       [<ffffffff815209d4>] compat_do_readv_writev+0x2d4/0x6e0 fs/read_write.c:982
       [<ffffffff815210ec>] compat_writev+0xdc/0x150 fs/read_write.c:1090
       [<ffffffff81523468>] C_SYSC_writev fs/read_write.c:1110 [inline]
       [<ffffffff81523468>] compat_SyS_writev+0xd8/0x1b0 fs/read_write.c:1099
       [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
       [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
       [<ffffffff8377b2aa>] sysenter_flags_fixed+0xd/0x17

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&(&q->lock)->rlock#2);
                               lock(_xmit_NETROM);
                               lock(&(&q->lock)->rlock#2);
  lock(_xmit_NETROM);

 *** DEADLOCK ***

9 locks held by syz-executor1/12601:
 #0:  (rcu_read_lock){......}, at: [<ffffffff82e55c5f>] __skb_unlink include/linux/skbuff.h:1643 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff82e55c5f>] __skb_dequeue include/linux/skbuff.h:1659 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff82e55c5f>] process_backlog+0x1af/0x690 net/core/dev.c:4644
 #1:  (rcu_read_lock){......}, at: [<ffffffff83315dd0>] dst_input include/net/dst.h:504 [inline]
 #1:  (rcu_read_lock){......}, at: [<ffffffff83315dd0>] ip6_input_finish+0x0/0x1540 net/ipv6/ip6_input.c:62
 #2:  (&(&q->lock)->rlock#2){+.-...}, at: [<ffffffff833a0627>] spin_lock include/linux/spinlock.h:302 [inline]
 #2:  (&(&q->lock)->rlock#2){+.-...}, at: [<ffffffff833a0627>] ipv6_frag_rcv+0x5e7/0x5020 net/ipv6/reassembly.c:560
 #3:  (slock-AF_INET6){+.-...}, at: [<ffffffff8338622a>] spin_trylock include/linux/spinlock.h:312 [inline]
 #3:  (slock-AF_INET6){+.-...}, at: [<ffffffff8338622a>] icmpv6_xmit_lock net/ipv6/icmp.c:120 [inline]
 #3:  (slock-AF_INET6){+.-...}, at: [<ffffffff8338622a>] icmp6_send+0x92a/0x1b70 net/ipv6/icmp.c:485
 #4:  (rcu_read_lock){......}, at: [<ffffffff833868d4>] icmp6_send+0xfd4/0x1b70 net/ipv6/icmp.c:517
 #5:  (rcu_read_lock_bh){......}, at: [<ffffffff83308d65>] ip6_finish_output2+0x1d5/0x1c60 net/ipv6/ip6_output.c:71
 #6:  (rcu_read_lock){......}, at: [<ffffffff833661c4>] ip6_nd_hdr net/ipv6/ndisc.c:427 [inline]
 #6:  (rcu_read_lock){......}, at: [<ffffffff833661c4>] ndisc_send_skb+0x654/0xf80 net/ipv6/ndisc.c:465
 #7:  (rcu_read_lock_bh){......}, at: [<ffffffff83308d65>] ip6_finish_output2+0x1d5/0x1c60 net/ipv6/ip6_output.c:71
 #8:  (rcu_read_lock_bh){......}, at: [<ffffffff82e5e0b5>] __dev_queue_xmit+0x1d5/0x1cc0 net/core/dev.c:3139

stack backtrace:
CPU: 1 PID: 12601 Comm: syz-executor1 Not tainted 4.4.125-g38f41ec #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 4df271c8b9e7339d ffff8801db3062f8 ffffffff81d067bd
 ffffffff851c1f60 ffffffff851c1f60 ffffffff851ea250 ffff8800a33eba48
 ffff8800a33eb000 ffff8801db306340 ffffffff81234081 ffff8800a33eba48
Call Trace:
 <IRQ>  [<ffffffff81d067bd>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ>  [<ffffffff81d067bd>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81234081>] print_circular_bug+0x271/0x310 kernel/locking/lockdep.c:1226
 [<ffffffff8123b00f>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
 [<ffffffff8123b00f>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
 [<ffffffff8123b00f>] validate_chain kernel/locking/lockdep.c:2144 [inline]
 [<ffffffff8123b00f>] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213
 [<ffffffff8123dcae>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
 [<ffffffff83778ad6>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
 [<ffffffff83778ad6>] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151
 [<ffffffff82ee5f7c>] spin_lock include/linux/spinlock.h:302 [inline]
 [<ffffffff82ee5f7c>] __netif_tx_lock include/linux/netdevice.h:3299 [inline]
 [<ffffffff82ee5f7c>] sch_direct_xmit+0x23c/0x760 net/sched/sch_generic.c:163
 [<ffffffff82e5f36e>] __dev_xmit_skb net/core/dev.c:2957 [inline]
 [<ffffffff82e5f36e>] __dev_queue_xmit+0x148e/0x1cc0 net/core/dev.c:3175
 [<ffffffff82e5fbb7>] dev_queue_xmit+0x17/0x20 net/core/dev.c:3241
 [<ffffffff82e7dd19>] neigh_resolve_output+0x469/0x770 net/core/neighbour.c:1312
 [<ffffffff83309520>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff83309520>] ip6_finish_output2+0x990/0x1c60 net/ipv6/ip6_output.c:113
 [<ffffffff833129d6>] ip6_finish_output+0x2e6/0x750 net/ipv6/ip6_output.c:131
 [<ffffffff83312feb>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff83312feb>] ip6_output+0x1ab/0x520 net/ipv6/ip6_output.c:145
 [<ffffffff8336557a>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff8336557a>] NF_HOOK_THRESH.constprop.24+0x11a/0x320 include/linux/netfilter.h:226
 [<ffffffff83366386>] NF_HOOK include/linux/netfilter.h:249 [inline]
 [<ffffffff83366386>] ndisc_send_skb+0x816/0xf80 net/ipv6/ndisc.c:471
 [<ffffffff8336a0d6>] ndisc_send_ns+0x2e6/0x720 net/ipv6/ndisc.c:595
 [<ffffffff8336a7b0>] ndisc_solicit+0x2a0/0x440 net/ipv6/ndisc.c:686
 [<ffffffff82e70e23>] neigh_probe+0xc3/0x100 net/core/neighbour.c:863
 [<ffffffff82e7b490>] __neigh_event_send+0x790/0xc40 net/core/neighbour.c:1019
 [<ffffffff82e7dd5a>] neigh_event_send include/net/neighbour.h:431 [inline]
 [<ffffffff82e7dd5a>] neigh_resolve_output+0x4aa/0x770 net/core/neighbour.c:1296
 [<ffffffff83309520>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff83309520>] ip6_finish_output2+0x990/0x1c60 net/ipv6/ip6_output.c:113
 [<ffffffff833129d6>] ip6_finish_output+0x2e6/0x750 net/ipv6/ip6_output.c:131
 [<ffffffff83312feb>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff83312feb>] ip6_output+0x1ab/0x520 net/ipv6/ip6_output.c:145
 [<ffffffff834209d5>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff834209d5>] ip6_local_out+0x95/0x170 net/ipv6/output_core.c:169
 [<ffffffff83315031>] ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1717
 [<ffffffff83315383>] ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1737
 [<ffffffff83385708>] icmpv6_push_pending_frames+0x338/0x530 net/ipv6/icmp.c:276
 [<ffffffff83386d6d>] icmp6_send+0x146d/0x1b70 net/ipv6/icmp.c:537
 [<ffffffff83388a29>] icmpv6_param_prob+0x29/0x40 net/ipv6/icmp.c:551
 [<ffffffff833a4050>] ip6_frag_queue net/ipv6/reassembly.c:263 [inline]
 [<ffffffff833a4050>] ipv6_frag_rcv+0x4010/0x5020 net/ipv6/reassembly.c:562
 [<ffffffff833160f9>] ip6_input_finish+0x329/0x1540 net/ipv6/ip6_input.c:248
 [<ffffffff83319276>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
 [<ffffffff83319276>] NF_HOOK include/linux/netfilter.h:249 [inline]
 [<ffffffff83319276>] ip6_input+0x106/0x200 net/ipv6/ip6_input.c:280
 [<ffffffff833158d8>] dst_input include/net/dst.h:504 [inline]
 [<ffffffff833158d8>] ip6_rcv_finish+0x138/0x630 net/ipv6/ip6_input.c:62
 [<ffffffff83318365>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
 [<ffffffff83318365>] NF_HOOK include/linux/netfilter.h:249 [inline]
 [<ffffffff83318365>] ipv6_rcv+0x1055/0x1e60 net/ipv6/ip6_input.c:186
 [<ffffffff82e51d99>] __netif_receive_skb_core+0xa59/0x28f0 net/core/dev.c:4019
 [<ffffffff82e53c8b>] __netif_receive_skb+0x5b/0x1c0 net/core/dev.c:4054
 [<ffffffff82e55cc3>] process_backlog+0x213/0x690 net/core/dev.c:4647
 [<ffffffff82e54fb3>] napi_poll net/core/dev.c:4885 [inline]
 [<ffffffff82e54fb3>] net_rx_action+0x373/0xe70 net/core/dev.c:4950
 [<ffffffff8377ce17>] __do_softirq+0x227/0xa38 kernel/softirq.c:273
 [<ffffffff8377abdc>] do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:929
 <EOI>  [<ffffffff8113bfb4>] do_softirq.part.17+0x54/0x60 kernel/softirq.c:317
 [<ffffffff8113dba9>] do_softirq+0x19/0x20 kernel/softirq.c:320
 [<ffffffff82e50616>] netif_rx_ni+0x166/0x3a0 net/core/dev.c:3653
 [<ffffffff826602d4>] tun_get_user+0xc74/0x2340 drivers/net/tun.c:1264
 [<ffffffff82661bb5>] tun_chr_write_iter+0xd5/0x190 drivers/net/tun.c:1283
 [<ffffffff8151e9f8>] do_iter_readv_writev+0x138/0x1e0 fs/read_write.c:664
 [<ffffffff815209d4>] compat_do_readv_writev+0x2d4/0x6e0 fs/read_write.c:982
 [<ffffffff815210ec>] compat_writev+0xdc/0x150 fs/read_write.c:1090
 [<ffffffff81523468>] C_SYSC_writev fs/read_write.c:1110 [inline]
 [<ffffffff81523468>] compat_SyS_writev+0xd8/0x1b0 fs/read_write.c:1099
 [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
 [<ffffffff8377b2aa>] sysenter_flags_fixed+0xd/0x17
IPVS: set_ctl: invalid protocol: 4 224.0.0.2:20000 fo
IPVS: set_ctl: invalid protocol: 4 224.0.0.2:20000 fo