TCP: request_sock_TCP: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
INFO: task syz-executor0:10994 blocked for more than 120 seconds.
      Not tainted 4.9.89-gf152ce1 #5
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D27120 10994   5826 0x20020004
 ffff8801cdf4c800 0000000000000000 ffff8801ccab64c0 ffff8801cd6e1800
 ffff8801db321b98 ffff8801cd1ef2b0 ffffffff838a4c0b 0000000041b58ab3
 ffffffff84193da8 00ffffff81239af0 ffff8801db322468 ffff8801db322490
Call Trace:
 [<ffffffff838a61af>] schedule+0x7f/0x1b0 kernel/sched/core.c:3551
 [<ffffffff838b216c>] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768
 [<ffffffff838a43be>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5173
 [<ffffffff81636c5e>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff81636c5e>] dio_await_one fs/direct-io.c:461 [inline]
 [<ffffffff81636c5e>] dio_await_completion fs/direct-io.c:515 [inline]
 [<ffffffff81636c5e>] do_blockdev_direct_IO+0x481e/0x7ab0 fs/direct-io.c:1331
 [<ffffffff81639f95>] __blockdev_direct_IO+0xa5/0xd0 fs/direct-io.c:1360
 [<ffffffff816290d0>] blkdev_direct_IO+0xa0/0xd0 fs/block_dev.c:183
 [<ffffffff8143ac73>] generic_file_read_iter+0x793/0x1ac0 mm/filemap.c:1952
 [<ffffffff8162a0c5>] blkdev_read_iter+0x105/0x170 fs/block_dev.c:1738
 [<ffffffff8160e964>] generic_file_splice_read+0x294/0x510 fs/splice.c:309
 [<ffffffff8160d11a>] do_splice_to+0x10a/0x160 fs/splice.c:899
 [<ffffffff8160d3bd>] splice_direct_to_actor+0x24d/0x800 fs/splice.c:971
 [<ffffffff8160db17>] do_splice_direct+0x1a7/0x270 fs/splice.c:1080
 [<ffffffff81570aeb>] do_sendfile+0x54b/0xd30 fs/read_write.c:1393
 [<ffffffff81572ba1>] C_SYSC_sendfile fs/read_write.c:1469 [inline]
 [<ffffffff81572ba1>] compat_SyS_sendfile+0xd1/0x160 fs/read_write.c:1458
 [<ffffffff81006f95>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006f95>] do_fast_syscall_32+0x2f5/0x870 arch/x86/entry/common.c:387
 [<ffffffff838b7210>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

Showing all locks held in the system:
2 locks held by khungtaskd/515:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81370ca5>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81370ca5>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81235c50>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3655:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d1a3f>] __fdget_pos+0x9f/0xc0 fs/file.c:781
2 locks held by getty/3784:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b3ce2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82008bc4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133

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

NMI backtrace for cpu 0
CPU: 0 PID: 515 Comm: khungtaskd Not tainted 4.9.89-gf152ce1 #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9197d00 ffffffff81d93609 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810bb690 ffff8801d9197d38
 ffffffff81d9e72d 0000000000000000 0000000000000000 ffff8801cd11b418
Call Trace:
 [<ffffffff81d93609>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d93609>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9e72d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9e867>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bb784>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81371270>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81371270>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81371270>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81371270>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119af4d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b5c9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3808 Comm: syz-fuzzer Not tainted 4.9.89-gf152ce1 #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d75b1800 task.stack: ffff8801b1a18000
RIP: 0010:[<ffffffff8153b254>] 
c [<ffffffff8153b254>] memset+0x4/0x40 mm/kasan/kasan.c:342
RSP: 0018:ffff8801b1a1f538  EFLAGS: 00000286
RAX: ffff8801d75b1800 RBX: ffff8801b1a1f618 RCX: ffff8801b1a1f618
RDX: 0000000000000040 RSI: 0000000000000000 RDI: ffff8801b1a1f5b0
RBP: ffff8801b1a1f538 R08: 1ffff1003aeb641a R09: ffffed0039b11318
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8801d75b1800 R14: ffff8801b1a1f5b0 R15: ffff8801b1a1f5d8
FS:  000000c420026768(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000256f000 CR3: 00000001da394000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801b1a1f5a0
c ffffffff810d517d
c ffff8801d75b20b0
c 1ffff10036343eac
c
 ffffffff853188c8
c 0000000041b58ab3
c ffffffff84193da8
c ffffffff81239af0
c
 ffff8801b1a1f638
c 0000000000000000
c 0000000000000000
c ffff8801d75b1800
c
Call Trace:
 [<ffffffff810d517d>] __unwind_start+0x2d/0x3c0 arch/x86/kernel/unwind_frame.c:66
 [<ffffffff8107c809>] unwind_start arch/x86/include/asm/unwind.h:39 [inline]
 [<ffffffff8107c809>] __save_stack_trace+0x59/0xf0 arch/x86/kernel/stacktrace.c:41
 [<ffffffff8107c8b6>] save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 [<ffffffff8153ade3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:505
 [<ffffffff8153b802>] set_track mm/kasan/kasan.c:517 [inline]
 [<ffffffff8153b802>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:582
 [<ffffffff81537af7>] slab_free_hook mm/slub.c:1355 [inline]
 [<ffffffff81537af7>] slab_free_freelist_hook mm/slub.c:1377 [inline]
 [<ffffffff81537af7>] slab_free mm/slub.c:2958 [inline]
 [<ffffffff81537af7>] kmem_cache_free+0xc7/0x300 mm/slub.c:2980
 [<ffffffff82ef07b7>] kfree_skbmem+0xd7/0xf0 net/core/skbuff.c:623
 [<ffffffff82ef597d>] __kfree_skb+0x1d/0x20 net/core/skbuff.c:685
 [<ffffffff8322d2ca>] sk_eat_skb include/net/sock.h:2201 [inline]
 [<ffffffff8322d2ca>] tcp_recvmsg+0x1b3a/0x2800 net/ipv4/tcp.c:1926
 [<ffffffff832f2dc6>] inet_recvmsg+0x306/0x4c0 net/ipv4/af_inet.c:801
 [<ffffffff82ed61a9>] sock_recvmsg_nosec net/socket.c:737 [inline]
 [<ffffffff82ed61a9>] sock_recvmsg+0xc9/0x110 net/socket.c:744
 [<ffffffff82ed6445>] sock_read_iter+0x255/0x370 net/socket.c:821
 [<ffffffff8156a28c>] new_sync_read fs/read_write.c:439 [inline]
 [<ffffffff8156a28c>] __vfs_read+0x4bc/0x670 fs/read_write.c:451
 [<ffffffff8156ddee>] vfs_read+0x11e/0x380 fs/read_write.c:472
 [<ffffffff81571ae9>] SYSC_read fs/read_write.c:588 [inline]
 [<ffffffff81571ae9>] SyS_read+0xd9/0x1b0 fs/read_write.c:581
 [<ffffffff81006504>] do_syscall_64+0x1a4/0x490 arch/x86/entry/common.c:282
 [<ffffffff838b5ad3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
cee 
c48 
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c77 
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c48 
c89 
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c5d 
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c00 
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c84 
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c86 
c68 
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c5d 
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c1f 
c40 
c00 
c55 
c48 
c89 
ce5 
c<41> 
c55 
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c89 
cf5 
c48 
c8b 
c4d 
c08 
c41 
c54 
c49 
c89 
cd4 
cba 
c01 
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c00 
c00 
c53 
c4c 
c