======================================================
[ INFO: possible circular locking dependency detected ]
4.4.153+ #91 Not tainted
-------------------------------------------------------
syz-executor142/2257 is trying to acquire lock:
 (&(&q->lock)->rlock){+.-...}, at: [<ffffffff823233bb>] spin_lock include/linux/spinlock.h:302 [inline]
 (&(&q->lock)->rlock){+.-...}, at: [<ffffffff823233bb>] ip_defrag+0x31b/0x40c0 net/ipv4/ip_fragment.c:680

but task is already holding lock:
 (_xmit_NETROM){+.-...}, at: [<ffffffff8221dac3>] spin_lock include/linux/spinlock.h:302 [inline]
 (_xmit_NETROM){+.-...}, at: [<ffffffff8221dac3>] __netif_tx_lock include/linux/netdevice.h:3299 [inline]
 (_xmit_NETROM){+.-...}, at: [<ffffffff8221dac3>] sch_direct_xmit+0x233/0x6c0 net/sched/sch_generic.c:163

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       [<ffffffff811fa43e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff8267b97e>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:112 [inline]
       [<ffffffff8267b97e>] _raw_spin_lock_irqsave+0x4e/0x70 kernel/locking/spinlock.c:159
       [<ffffffff81adebdb>] depot_save_stack+0x20b/0x5eb lib/stackdepot.c:252
       [<ffffffff8145ed49>] save_stack mm/kasan/kasan.c:518 [inline]
       [<ffffffff8145ed49>] set_track mm/kasan/kasan.c:524 [inline]
       [<ffffffff8145ed49>] kasan_kmalloc.part.1+0xc9/0xf0 mm/kasan/kasan.c:616
       [<ffffffff8145ef5f>] kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:601
       [<ffffffff8145f522>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
       [<ffffffff8145ae1a>] slab_post_alloc_hook mm/slub.c:1349 [inline]
       [<ffffffff8145ae1a>] slab_alloc_node mm/slub.c:2615 [inline]
       [<ffffffff8145ae1a>] slab_alloc mm/slub.c:2623 [inline]
       [<ffffffff8145ae1a>] kmem_cache_alloc+0xba/0x2a0 mm/slub.c:2628
       [<ffffffff8231d91d>] inet_getpeer+0x159d/0x1d70 net/ipv4/inetpeer.c:444
       [<ffffffff82588607>] inet_getpeer_v6 include/net/inetpeer.h:127 [inline]
       [<ffffffff82588607>] icmpv6_xrlim_allow net/ipv6/icmp.c:211 [inline]
       [<ffffffff82588607>] icmp6_send+0x17b7/0x1b70 net/ipv6/icmp.c:491
       [<ffffffff82589dc9>] icmpv6_param_prob+0x29/0x40 net/ipv6/icmp.c:551
       [<ffffffff825a52a6>] ip6_frag_queue net/ipv6/reassembly.c:263 [inline]
       [<ffffffff825a52a6>] ipv6_frag_rcv+0x3de6/0x4f80 net/ipv6/reassembly.c:562
       [<ffffffff82519f5d>] ip6_input_finish+0x57d/0x1510 net/ipv6/ip6_input.c:248
       [<ffffffff8251ccf6>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
       [<ffffffff8251ccf6>] NF_HOOK include/linux/netfilter.h:249 [inline]
       [<ffffffff8251ccf6>] ip6_input+0xf6/0x200 net/ipv6/ip6_input.c:280
       [<ffffffff825194be>] dst_input include/net/dst.h:504 [inline]
       [<ffffffff825194be>] ip6_rcv_finish+0x14e/0x670 net/ipv6/ip6_input.c:62
       [<ffffffff8251bfa2>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
       [<ffffffff8251bfa2>] NF_HOOK include/linux/netfilter.h:249 [inline]
       [<ffffffff8251bfa2>] ipv6_rcv+0x10b2/0x1d10 net/ipv6/ip6_input.c:186
       [<ffffffff8219d748>] __netif_receive_skb_core+0x12c8/0x2820 net/core/dev.c:4019
       [<ffffffff821a54db>] __netif_receive_skb+0x5b/0x1c0 net/core/dev.c:4054
       [<ffffffff821ac43a>] process_backlog+0x20a/0x670 net/core/dev.c:4647
       [<ffffffff821ab8cc>] napi_poll net/core/dev.c:4885 [inline]
       [<ffffffff821ab8cc>] net_rx_action+0x2ec/0xc50 net/core/dev.c:4950
       [<ffffffff8267f59c>] __do_softirq+0x22c/0xa1a kernel/softirq.c:273
       [<ffffffff8267d79c>] do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:929
       [<ffffffff810deaa4>] do_softirq.part.2+0x54/0x60 kernel/softirq.c:317
       [<ffffffff810debf9>] do_softirq+0x19/0x20 kernel/softirq.c:320
       [<ffffffff8219bdac>] netif_rx_ni+0xec/0x3a0 net/core/dev.c:3653
       [<ffffffff81da7f5a>] tun_get_user+0xf3a/0x2690 drivers/net/tun.c:1264
       [<ffffffff81da98c5>] tun_chr_write_iter+0xd5/0x190 drivers/net/tun.c:1283
       [<ffffffff81471e13>] do_iter_readv_writev+0x133/0x1d0 fs/read_write.c:664
       [<ffffffff81473145>] do_readv_writev+0x335/0x6f0 fs/read_write.c:808
       [<ffffffff8147362b>] vfs_writev+0x7b/0xb0 fs/read_write.c:847
       [<ffffffff81475b09>] SYSC_writev fs/read_write.c:880 [inline]
       [<ffffffff81475b09>] SyS_writev+0xd9/0x250 fs/read_write.c:872
       [<ffffffff8267c6a1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff811f6aee>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
       [<ffffffff811f6aee>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
       [<ffffffff811f6aee>] validate_chain kernel/locking/lockdep.c:2144 [inline]
       [<ffffffff811f6aee>] __lock_acquire+0x3b6e/0x5ba0 kernel/locking/lockdep.c:3213
       [<ffffffff811fa43e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff8267b7c6>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
       [<ffffffff8267b7c6>] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151
       [<ffffffff823233bb>] spin_lock include/linux/spinlock.h:302 [inline]
       [<ffffffff823233bb>] ip_defrag+0x31b/0x40c0 net/ipv4/ip_fragment.c:680
       [<ffffffff82327507>] ip_check_defrag+0x3a7/0x710 net/ipv4/ip_fragment.c:724
       [<ffffffff826461aa>] packet_rcv_fanout+0x52a/0x5e0 net/packet/af_packet.c:1458
       [<ffffffff821b1540>] dev_queue_xmit_nit net/core/dev.c:1913 [inline]
       [<ffffffff821b1540>] xmit_one net/core/dev.c:2755 [inline]
       [<ffffffff821b1540>] dev_hard_start_xmit+0x650/0x11c0 net/core/dev.c:2775
       [<ffffffff8221db48>] sch_direct_xmit+0x2b8/0x6c0 net/sched/sch_generic.c:165
       [<ffffffff821b3305>] __dev_xmit_skb net/core/dev.c:2957 [inline]
       [<ffffffff821b3305>] __dev_queue_xmit+0xf95/0x1c30 net/core/dev.c:3175
       [<ffffffff821b3fb7>] dev_queue_xmit+0x17/0x20 net/core/dev.c:3241
       [<ffffffff821d3cc0>] neigh_resolve_output+0x600/0x780 net/core/neighbour.c:1326
       [<ffffffff8232ee60>] dst_neigh_output include/net/dst.h:461 [inline]
       [<ffffffff8232ee60>] ip_finish_output2+0x8f0/0x1100 net/ipv4/ip_output.c:213
       [<ffffffff823316e0>] ip_do_fragment+0x1870/0x1f60 net/ipv4/ip_output.c:635
       [<ffffffff823353b5>] ip_fragment.constprop.5+0x145/0x200 net/ipv4/ip_output.c:505
       [<ffffffff82335806>] ip_finish_output+0x396/0xc00 net/ipv4/ip_output.c:286
       [<ffffffff82338f87>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
       [<ffffffff82338f87>] ip_mc_output+0x237/0x980 net/ipv4/ip_output.c:347
       [<ffffffff8233680b>] dst_output include/net/dst.h:498 [inline]
       [<ffffffff8233680b>] ip_local_out+0x9b/0x180 net/ipv4/ip_output.c:119
       [<ffffffff8233c52c>] ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1453
       [<ffffffff823e1ad3>] udp_send_skb+0x503/0xc70 net/ipv4/udp.c:842
       [<ffffffff823e8959>] udp_sendmsg+0x16c9/0x1c70 net/ipv4/udp.c:1072
       [<ffffffff82411bf3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
       [<ffffffff8214696b>] sock_sendmsg_nosec net/socket.c:638 [inline]
       [<ffffffff8214696b>] sock_sendmsg+0xbb/0x110 net/socket.c:648
       [<ffffffff8214ab70>] SYSC_sendto net/socket.c:1678 [inline]
       [<ffffffff8214ab70>] SyS_sendto+0x220/0x370 net/socket.c:1646
       [<ffffffff8267c6a1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

4 locks held by syz-executor142/2257:
 #0:  (rcu_read_lock_bh){......}, at: [<ffffffff8232e77b>] ip_finish_output2+0x20b/0x1100 net/ipv4/ip_output.c:193
 #1:  (rcu_read_lock_bh){......}, at: [<ffffffff821b2547>] __dev_queue_xmit+0x1d7/0x1c30 net/core/dev.c:3139
 #2:  (_xmit_NETROM){+.-...}, at: [<ffffffff8221dac3>] spin_lock include/linux/spinlock.h:302 [inline]
 #2:  (_xmit_NETROM){+.-...}, at: [<ffffffff8221dac3>] __netif_tx_lock include/linux/netdevice.h:3299 [inline]
 #2:  (_xmit_NETROM){+.-...}, at: [<ffffffff8221dac3>] sch_direct_xmit+0x233/0x6c0 net/sched/sch_generic.c:163
 #3:  (rcu_read_lock){......}, at: [<ffffffff821b0f98>] xmit_one net/core/dev.c:2754 [inline]
 #3:  (rcu_read_lock){......}, at: [<ffffffff821b0f98>] dev_hard_start_xmit+0xa8/0x11c0 net/core/dev.c:2775

stack backtrace:
CPU: 0 PID: 2257 Comm: syz-executor142 Not tainted 4.4.153+ #91
 0000000000000000 33381196c29a3fda ffff8800aef7ed88 ffffffff81a4510d
 ffffffff83ac5550 ffffffff83ac5c10 ffffffff83ac5550 ffff8800af04e838
 ffff8800af04df00 ffff8800aef7edd0 ffffffff81391172 0000000000000003
Call Trace:
 [<ffffffff81a4510d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81a4510d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81391172>] print_circular_bug.cold.34+0x2f7/0x432 kernel/locking/lockdep.c:1226
 [<ffffffff811f6aee>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
 [<ffffffff811f6aee>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
 [<ffffffff811f6aee>] validate_chain kernel/locking/lockdep.c:2144 [inline]
 [<ffffffff811f6aee>] __lock_acquire+0x3b6e/0x5ba0 kernel/locking/lockdep.c:3213
 [<ffffffff811fa43e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff8267b7c6>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
 [<ffffffff8267b7c6>] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151
 [<ffffffff823233bb>] spin_lock include/linux/spinlock.h:302 [inline]
 [<ffffffff823233bb>] ip_defrag+0x31b/0x40c0 net/ipv4/ip_fragment.c:680
 [<ffffffff82327507>] ip_check_defrag+0x3a7/0x710 net/ipv4/ip_fragment.c:724
 [<ffffffff826461aa>] packet_rcv_fanout+0x52a/0x5e0 net/packet/af_packet.c:1458
 [<ffffffff821b1540>] dev_queue_xmit_nit net/core/dev.c:1913 [inline]
 [<ffffffff821b1540>] xmit_one net/core/dev.c:2755 [inline]
 [<ffffffff821b1540>] dev_hard_start_xmit+0x650/0x11c0 net/core/dev.c:2775
 [<ffffffff8221db48>] sch_direct_xmit+0x2b8/0x6c0 net/sched/sch_generic.c:165
 [<ffffffff821b3305>] __dev_xmit_skb net/core/dev.c:2957 [inline]
 [<ffffffff821b3305>] __dev_queue_xmit+0xf95/0x1c30 net/core/dev.c:3175
 [<ffffffff821b3fb7>] dev_queue_xmit+0x17/0x20 net/core/dev.c:3241
 [<ffffffff821d3cc0>] neigh_resolve_output+0x600/0x780 net/core/neighbour.c:1326
 [<ffffffff8232ee60>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff8232ee60>] ip_finish_output2+0x8f0/0x1100 net/ipv4/ip_output.c:213
 [<ffffffff823316e0>] ip_do_fragment+0x1870/0x1f60 net/ipv4/ip_output.c:635
 [<ffffffff823353b5>] ip_fragment.constprop.5+0x145/0x200 net/ipv4/ip_output.c:505
 [<ffffffff82335806>] ip_finish_output+0x396/0xc00 net/ipv4/ip_output.c:286
 [<ffffffff82338f87>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff82338f87>] ip_mc_output+0x237/0x980 net/ipv4/ip_output.c:347
 [<ffffffff8233680b>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff8233680b>] ip_local_out+0x9b/0x180 net/ipv4/ip_output.c:119
 [<ffffffff8233c52c>] ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1453
 [<ffffffff823e1ad3>] udp_send_skb+0x503/0xc70 net/ipv4/udp.c:842
 [<ffffffff823e8959>] udp_sendmsg+0x16c9/0x1c70 net/ipv4/udp.c:1072
 [<ffffffff82411bf3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff8214696b>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff8214696b>] sock_sendmsg+0xbb/0x110 net/socket.c:648
 [<ffffffff8214ab70>] SYSC_sendto net/socket.c:1678 [inline]
 [<ffffffff8214ab70>] SyS_sendto+0x220/0x370 net/socket.c:1646
 [<ffffffff8267c6a1>] entry_SYSCALL_64_fastpath+0x1e/0x9a