======================================================
[ INFO: possible circular locking dependency detected ]
4.4.174+ #17 Not tainted
-------------------------------------------------------
syz-executor.4/22055 is trying to acquire lock:
 (&(&q->lock)->rlock){+.-...}, at: [<ffffffff823ba312>] spin_lock include/linux/spinlock.h:302 [inline]
 (&(&q->lock)->rlock){+.-...}, at: [<ffffffff823ba312>] ip_defrag+0x322/0x3b70 net/ipv4/ip_fragment.c:690

but task is already holding lock:
 (_xmit_NETROM){+.-...}, at: [<ffffffff822b1b58>] spin_lock include/linux/spinlock.h:302 [inline]
 (_xmit_NETROM){+.-...}, at: [<ffffffff822b1b58>] __netif_tx_lock include/linux/netdevice.h:3306 [inline]
 (_xmit_NETROM){+.-...}, at: [<ffffffff822b1b58>] sch_direct_xmit+0x238/0x700 net/sched/sch_generic.c:163

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       [<ffffffff81205f6e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff82717c98>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
       [<ffffffff82717c98>] _raw_spin_lock+0x38/0x50 kernel/locking/spinlock.c:151
       [<ffffffff82308f92>] spin_lock include/linux/spinlock.h:302 [inline]
       [<ffffffff82308f92>] __instance_destroy+0xc2/0x180 net/netfilter/nfnetlink_log.c:222
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket
       [<ffffffff823091c7>] nfulnl_rcv_nl_event+0x177/0x200 net/netfilter/nfnetlink_log.c:780
       [<ffffffff81137e69>] notifier_call_chain+0xb9/0x1e0 kernel/notifier.c:93
       [<ffffffff81138097>] __atomic_notifier_call_chain+0x87/0x150 kernel/notifier.c:183
       [<ffffffff8113818e>] atomic_notifier_call_chain+0x2e/0x40 kernel/notifier.c:193
       [<ffffffff822edca7>] netlink_release+0xe37/0x1590 net/netlink/af_netlink.c:760
       [<ffffffff821d36a5>] __sock_release+0xd5/0x260 net/socket.c:592
       [<ffffffff821d384b>] sock_close+0x1b/0x30 net/socket.c:1050
       [<ffffffff8149c8c6>] __fput+0x246/0x710 fs/file_table.c:208
       [<ffffffff8149ce16>] ____fput+0x16/0x20 fs/file_table.c:244
       [<ffffffff8112f352>] task_work_run+0x202/0x2b0 kernel/task_work.c:115
       [<ffffffff81003dca>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
       [<ffffffff81003dca>] exit_to_usermode_loop+0x14a/0x170 arch/x86/entry/common.c:188
       [<ffffffff810064b9>] prepare_exit_to_usermode arch/x86/entry/common.c:221 [inline]
       [<ffffffff810064b9>] syscall_return_slowpath arch/x86/entry/common.c:286 [inline]
       [<ffffffff810064b9>] do_syscall_32_irqs_on arch/x86/entry/common.c:336 [inline]
       [<ffffffff810064b9>] do_fast_syscall_32+0x7a9/0xa90 arch/x86/entry/common.c:397
       [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a

       [<ffffffff81202d86>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
       [<ffffffff81202d86>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
       [<ffffffff81202d86>] validate_chain kernel/locking/lockdep.c:2144 [inline]
       [<ffffffff81202d86>] __lock_acquire+0x37d6/0x4f50 kernel/locking/lockdep.c:3213
       [<ffffffff81205f6e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff82717c98>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
       [<ffffffff82717c98>] _raw_spin_lock+0x38/0x50 kernel/locking/spinlock.c:151
       [<ffffffff823ba312>] spin_lock include/linux/spinlock.h:302 [inline]
       [<ffffffff823ba312>] ip_defrag+0x322/0x3b70 net/ipv4/ip_fragment.c:690
       [<ffffffff823bdf36>] ip_check_defrag net/ipv4/ip_fragment.c:738 [inline]
       [<ffffffff823bdf36>] ip_check_defrag+0x3d6/0x5b0 net/ipv4/ip_fragment.c:705
       [<ffffffff826dfb3e>] packet_rcv_fanout+0x51e/0x5f0 net/packet/af_packet.c:1458
       [<ffffffff82244b38>] deliver_skb net/core/dev.c:1842 [inline]
       [<ffffffff82244b38>] dev_queue_xmit_nit net/core/dev.c:1898 [inline]
       [<ffffffff82244b38>] xmit_one net/core/dev.c:2777 [inline]
       [<ffffffff82244b38>] dev_hard_start_xmit+0x288/0x11e0 net/core/dev.c:2797
       [<ffffffff822b1bd6>] sch_direct_xmit+0x2b6/0x700 net/sched/sch_generic.c:165
       [<ffffffff82246aa4>] __dev_xmit_skb net/core/dev.c:2979 [inline]
       [<ffffffff82246aa4>] __dev_queue_xmit+0xd24/0x1bb0 net/core/dev.c:3197
       [<ffffffff82247948>] dev_queue_xmit+0x18/0x20 net/core/dev.c:3263
       [<ffffffff822677e0>] neigh_resolve_output+0x4a0/0x7a0 net/core/neighbour.c:1329
       [<ffffffff823c5412>] dst_neigh_output include/net/dst.h:461 [inline]
       [<ffffffff823c5412>] ip_finish_output2+0x6a2/0x1280 net/ipv4/ip_output.c:213
       [<ffffffff823c805c>] ip_do_fragment+0x187c/0x1f70 net/ipv4/ip_output.c:635
       [<ffffffff823cbd7b>] ip_fragment.constprop.0+0x14b/0x200 net/ipv4/ip_output.c:505
       [<ffffffff823cc1e9>] ip_finish_output+0x3b9/0xc60 net/ipv4/ip_output.c:286
       [<ffffffff823cf9f1>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
       [<ffffffff823cf9f1>] ip_mc_output+0x251/0xae0 net/ipv4/ip_output.c:347
       [<ffffffff823cd21c>] dst_output include/net/dst.h:498 [inline]
       [<ffffffff823cd21c>] ip_local_out+0x9c/0x180 net/ipv4/ip_output.c:119
       [<ffffffff823d300e>] ip_send_skb+0x3e/0xc0 net/ipv4/ip_output.c:1453
       [<ffffffff82478ded>] udp_send_skb+0x4fd/0xc70 net/ipv4/udp.c:842
       [<ffffffff824795ae>] udp_push_pending_frames+0x4e/0xe0 net/ipv4/udp.c:870
       [<ffffffff8248084e>] udp_sendpage+0x2ae/0x410 net/ipv4/udp.c:1183
       [<ffffffff824aa083>] inet_sendpage+0x223/0x520 net/ipv4/af_inet.c:772
       [<ffffffff821d81b5>] kernel_sendpage+0x95/0xf0 net/socket.c:3320
       [<ffffffff821d829b>] sock_sendpage+0x8b/0xc0 net/socket.c:793
       [<ffffffff81530f1d>] pipe_to_sendpage+0x28d/0x3d0 fs/splice.c:724
       [<ffffffff81533b6e>] splice_from_pipe_feed fs/splice.c:776 [inline]
       [<ffffffff81533b6e>] __splice_from_pipe+0x37e/0x7a0 fs/splice.c:901
       [<ffffffff81536be8>] splice_from_pipe+0x108/0x170 fs/splice.c:936
       [<ffffffff81536c8c>] generic_splice_sendpage+0x3c/0x50 fs/splice.c:1109
       [<ffffffff81537d31>] do_splice_from fs/splice.c:1128 [inline]
       [<ffffffff81537d31>] do_splice fs/splice.c:1404 [inline]
       [<ffffffff81537d31>] SYSC_splice fs/splice.c:1707 [inline]
       [<ffffffff81537d31>] SyS_splice+0xd71/0x13a0 fs/splice.c:1690
       [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
       [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
       [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a

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 ***

6 locks held by syz-executor.4/22055:
 #0:  (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814af8b3>] pipe_lock_nested fs/pipe.c:65 [inline]
 #0:  (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814af8b3>] pipe_lock+0x63/0x80 fs/pipe.c:73
 #1:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff824806d2>] lock_sock include/net/sock.h:1497 [inline]
 #1:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff824806d2>] udp_sendpage+0x132/0x410 net/ipv4/udp.c:1160
 #2:  (rcu_read_lock_bh){......}, at: [<ffffffff823c4f7b>] ip_finish_output2+0x20b/0x1280 net/ipv4/ip_output.c:193
 #3:  (rcu_read_lock_bh){......}, at: [<ffffffff82245f57>] __dev_queue_xmit+0x1d7/0x1bb0 net/core/dev.c:3161
 #4:  (_xmit_NETROM){+.-...}, at: [<ffffffff822b1b58>] spin_lock include/linux/spinlock.h:302 [inline]
 #4:  (_xmit_NETROM){+.-...}, at: [<ffffffff822b1b58>] __netif_tx_lock include/linux/netdevice.h:3306 [inline]
 #4:  (_xmit_NETROM){+.-...}, at: [<ffffffff822b1b58>] sch_direct_xmit+0x238/0x700 net/sched/sch_generic.c:163
 #5:  (rcu_read_lock){......}, at: [<ffffffff82244963>] xmit_one net/core/dev.c:2776 [inline]
 #5:  (rcu_read_lock){......}, at: [<ffffffff82244963>] dev_hard_start_xmit+0xb3/0x11e0 net/core/dev.c:2797

stack backtrace:
CPU: 0 PID: 22055 Comm: syz-executor.4 Not tainted 4.4.174+ #17
 0000000000000000 dbb001933db19113 ffff8801934b6c40 ffffffff81aad1a1
 ffffffff84057a80 ffff8801da734740 ffffffff83af0370 ffffffff83ad4e60
 ffffffff83af0370 ffff8801934b6c90 ffffffff813abcda ffff8801934b6d70
Call Trace:
 [<ffffffff81aad1a1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aad1a1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff813abcda>] print_circular_bug.cold+0x2f7/0x44e kernel/locking/lockdep.c:1226
 [<ffffffff81202d86>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
 [<ffffffff81202d86>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
 [<ffffffff81202d86>] validate_chain kernel/locking/lockdep.c:2144 [inline]
 [<ffffffff81202d86>] __lock_acquire+0x37d6/0x4f50 kernel/locking/lockdep.c:3213
 [<ffffffff81205f6e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff82717c98>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
 [<ffffffff82717c98>] _raw_spin_lock+0x38/0x50 kernel/locking/spinlock.c:151
 [<ffffffff823ba312>] spin_lock include/linux/spinlock.h:302 [inline]
 [<ffffffff823ba312>] ip_defrag+0x322/0x3b70 net/ipv4/ip_fragment.c:690
 [<ffffffff823bdf36>] ip_check_defrag net/ipv4/ip_fragment.c:738 [inline]
 [<ffffffff823bdf36>] ip_check_defrag+0x3d6/0x5b0 net/ipv4/ip_fragment.c:705
 [<ffffffff826dfb3e>] packet_rcv_fanout+0x51e/0x5f0 net/packet/af_packet.c:1458
 [<ffffffff82244b38>] deliver_skb net/core/dev.c:1842 [inline]
 [<ffffffff82244b38>] dev_queue_xmit_nit net/core/dev.c:1898 [inline]
 [<ffffffff82244b38>] xmit_one net/core/dev.c:2777 [inline]
 [<ffffffff82244b38>] dev_hard_start_xmit+0x288/0x11e0 net/core/dev.c:2797
 [<ffffffff822b1bd6>] sch_direct_xmit+0x2b6/0x700 net/sched/sch_generic.c:165
 [<ffffffff82246aa4>] __dev_xmit_skb net/core/dev.c:2979 [inline]
 [<ffffffff82246aa4>] __dev_queue_xmit+0xd24/0x1bb0 net/core/dev.c:3197
 [<ffffffff82247948>] dev_queue_xmit+0x18/0x20 net/core/dev.c:3263
 [<ffffffff822677e0>] neigh_resolve_output+0x4a0/0x7a0 net/core/neighbour.c:1329
 [<ffffffff823c5412>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff823c5412>] ip_finish_output2+0x6a2/0x1280 net/ipv4/ip_output.c:213
 [<ffffffff823c805c>] ip_do_fragment+0x187c/0x1f70 net/ipv4/ip_output.c:635
 [<ffffffff823cbd7b>] ip_fragment.constprop.0+0x14b/0x200 net/ipv4/ip_output.c:505
 [<ffffffff823cc1e9>] ip_finish_output+0x3b9/0xc60 net/ipv4/ip_output.c:286
 [<ffffffff823cf9f1>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff823cf9f1>] ip_mc_output+0x251/0xae0 net/ipv4/ip_output.c:347
 [<ffffffff823cd21c>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff823cd21c>] ip_local_out+0x9c/0x180 net/ipv4/ip_output.c:119
 [<ffffffff823d300e>] ip_send_skb+0x3e/0xc0 net/ipv4/ip_output.c:1453
 [<ffffffff82478ded>] udp_send_skb+0x4fd/0xc70 net/ipv4/udp.c:842
 [<ffffffff824795ae>] udp_push_pending_frames+0x4e/0xe0 net/ipv4/udp.c:870
 [<ffffffff8248084e>] udp_sendpage+0x2ae/0x410 net/ipv4/udp.c:1183
 [<ffffffff824aa083>] inet_sendpage+0x223/0x520 net/ipv4/af_inet.c:772
 [<ffffffff821d81b5>] kernel_sendpage+0x95/0xf0 net/socket.c:3320
 [<ffffffff821d829b>] sock_sendpage+0x8b/0xc0 net/socket.c:793
 [<ffffffff81530f1d>] pipe_to_sendpage+0x28d/0x3d0 fs/splice.c:724
 [<ffffffff81533b6e>] splice_from_pipe_feed fs/splice.c:776 [inline]
 [<ffffffff81533b6e>] __splice_from_pipe+0x37e/0x7a0 fs/splice.c:901
 [<ffffffff81536be8>] splice_from_pipe+0x108/0x170 fs/splice.c:936
 [<ffffffff81536c8c>] generic_splice_sendpage+0x3c/0x50 fs/splice.c:1109
 [<ffffffff81537d31>] do_splice_from fs/splice.c:1128 [inline]
 [<ffffffff81537d31>] do_splice fs/splice.c:1404 [inline]
 [<ffffffff81537d31>] SYSC_splice fs/splice.c:1707 [inline]
 [<ffffffff81537d31>] SyS_splice+0xd71/0x13a0 fs/splice.c:1690
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket
binder: 22125:22127 ioctl c0046686 20000500 returned -22
audit: type=1400 audit(1566017761.449:151): avc:  denied  { mounton } for  pid=22126 comm="syz-executor.1" path="/proc/709/attr/exec" dev="proc" ino=71797 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=file permissive=1
binder: 22098:22131 BC_REQUEST_DEATH_NOTIFICATION invalid ref 0
binder: 22098:22131 transaction failed 29189/-22, size 0-0 line 3014
binder: 22125:22127 transaction failed 29189/-22, size 0-0 line 3014
binder: 22125:22127 ioctl c0046686 20000500 returned -22
binder: 22125:22132 transaction failed 29189/-22, size 0-0 line 3014
binder: 22098:22113 unknown command 536872192
binder: 22098:22113 ioctl c0306201 20008fd0 returned -22
binder: 22098:22122 transaction failed 29189/-22, size 0-0 line 3014
binder: 22145:22146 ioctl c0046686 20000500 returned -22
binder: 22145:22146 transaction failed 29189/-22, size 0-0 line 3014
binder: 22150:22151 ioctl c0046686 20000500 returned -22
binder: 22150:22151 transaction failed 29189/-22, size 0-0 line 3014
binder: 22161:22163 ioctl c0046686 20000500 returned -22
binder: 22161:22163 transaction failed 29189/-22, size 0-0 line 3014
binder: 22164:22166 ioctl c0046686 20000500 returned -22
binder: 22164:22166 transaction failed 29189/-22, size 0-0 line 3014
binder: 22179:22181 ioctl c0046686 20000500 returned -22
binder: 22180:22182 ioctl c0046686 20000500 returned -22
binder: 22180:22182 transaction failed 29189/-22, size 0-0 line 3014
binder: 22179:22181 transaction failed 29189/-22, size 0-0 line 3014
binder: 22192:22193 ioctl c0046686 20000500 returned -22
binder: 22194:22195 ioctl c0046686 20000500 returned -22
binder: 22192:22193 transaction failed 29189/-22, size 0-0 line 3014
binder: 22194:22195 transaction failed 29189/-22, size 0-0 line 3014
binder: 22201:22204 ioctl c0046686 20000500 returned -22
binder: 22200:22206 ioctl c0046686 20000500 returned -22
binder: 22201:22204 transaction failed 29189/-22, size 0-0 line 3014
binder: 22200:22206 transaction failed 29189/-22, size 0-0 line 3014
binder: 22214:22216 ioctl c0046686 20000500 returned -22
binder: 22215:22217 ioctl c0046686 20000500 returned -22
binder: 22215:22217 transaction failed 29189/-22, size 0-0 line 3014
binder: 22214:22227 transaction failed 29189/-22, size 0-0 line 3014
binder: 22226:22228 ioctl c0046686 20000500 returned -22
binder: 22226:22228 transaction failed 29189/-22, size 0-0 line 3014
binder: 22233:22234 ioctl c0046686 20000500 returned -22
binder: 22233:22234 transaction failed 29189/-22, size 0-0 line 3014
binder: 22238:22239 ioctl c0046686 20000500 returned -22
binder: 22238:22239 transaction failed 29189/-22, size 0-0 line 3014
binder: 22245:22249 ioctl c0046686 20000500 returned -22
binder: 22247:22251 ioctl c0046686 20000500 returned -22
binder: 22247:22251 transaction failed 29189/-22, size 0-0 line 3014
binder: 22245:22249 transaction failed 29189/-22, size 0-0 line 3014
binder: 22258:22259 ioctl c0046686 20000500 returned -22
binder: 22258:22259 transaction failed 29189/-22, size 0-0 line 3014
binder: 22267:22268 ioctl c0046686 20000500 returned -22
binder: 22267:22268 transaction failed 29189/-22, size 0-0 line 3014
binder: 22276:22278 ioctl c0046686 20000500 returned -22
binder: 22276:22278 transaction failed 29189/-22, size 0-0 line 3014
binder: 22286:22289 ioctl c0046686 20000500 returned -22
binder: 22285:22292 ioctl c0046686 20000500 returned -22
binder: 22286:22289 transaction failed 29189/-22, size 0-0 line 3014
binder: 22285:22292 transaction failed 29189/-22, size 0-0 line 3014
binder: 22301:22303 ioctl c0046686 20000500 returned -22
binder: 22301:22303 transaction failed 29189/-22, size 0-0 line 3014
binder: 22307:22309 ioctl c0046686 20000500 returned -22
binder: 22307:22309 transaction failed 29189/-22, size 0-0 line 3014
binder: 22311:22312 ioctl c0046686 20000500 returned -22
binder: 22311:22312 transaction failed 29189/-22, size 0-0 line 3014
binder: 22314:22315 ioctl c0046686 20000500 returned -22
binder: 22314:22315 transaction failed 29189/-22, size 0-0 line 3014
binder: 22326:22330 ioctl c0046686 20000500 returned -22
binder: 22329:22334 ioctl c0046686 20000500 returned -22
binder: 22326:22330 transaction failed 29189/-22, size 0-0 line 3014
binder: 22329:22334 transaction failed 29189/-22, size 0-0 line 3014
binder: 22343:22345 ioctl c0046686 20000500 returned -22
binder: 22344:22346 ioctl c0046686 20000500 returned -22
binder: 22344:22346 transaction failed 29189/-22, size 0-0 line 3014
binder: 22343:22345 transaction failed 29189/-22, size 0-0 line 3014
binder: 22352:22353 ioctl c0046686 20000500 returned -22
binder: 22352:22353 transaction failed 29189/-22, size 0-0 line 3014
binder: 22355:22356 ioctl c0046686 20000500 returned -22
binder: 22355:22356 transaction failed 29189/-22, size 0-0 line 3014
binder: 22359:22360 ioctl c0046686 20000500 returned -22
binder: 22359:22360 transaction failed 29189/-22, size 0-0 line 3014
binder: 22364:22366 ioctl c0046686 20000500 returned -22
binder: 22362:22367 ioctl c0046686 20000500 returned -22
binder: 22364:22366 transaction failed 29189/-22, size 0-0 line 3014
binder: 22362:22367 transaction failed 29189/-22, size 0-0 line 3014
binder: 22375:22376 ioctl c0046686 20000500 returned -22
binder: 22375:22376 transaction failed 29189/-22, size 0-0 line 3014
binder: 22381:22382 ioctl c0046686 20000500 returned -22
binder: 22381:22382 transaction failed 29189/-22, size 0-0 line 3014
binder: 22383:22384 transaction failed 29189/-22, size 0-0 line 3014
binder: 22390:22393 ioctl c0046686 20000500 returned -22
binder: 22400:22402 ioctl c0046686 20000500 returned -22