TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
PGD 80000001b3b3e067 P4D 80000001b3b3e067 PUD 1b3b38067 PMD 0 
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 4576 Comm: syz-fuzzer Not tainted 4.18.0-rc4+ #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kmsan_free_page+0xfc/0x2f0 mm/kmsan/kmsan_hooks.c:318
Code: 01 00 00 48 c7 00 00 00 00 00 44 39 e1 0f 8d b0 00 00 00 48 63 d1 48 8d 14 52 48 c1 e2 05 48 8b 54 13 40 48 83 c0 60 83 c1 01 <80> 7a 50 00 74 be 0f 0b 66 90 66 2e 0f 1f 84 00 00 00 00 00 eb fe 
RSP: 0018:ffff880197c9f5d8 EFLAGS: 00010002
RAX: ffffea000220abc8 RBX: ffffea0002208000 RCX: 0000000000000075
RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffffea00078e4000
RBP: ffff880197c9f628 R08: 0000000000480020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff81c6d720 R12: 0000000000000200
R13: ffff8801d0768000 R14: 0000000000000009 R15: ffffea0000624000
FS:  000000000234e628(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000050 CR3: 00000001abd70000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 free_pages_prepare mm/page_alloc.c:993 [inline]
 __free_pages_ok+0x267/0x1690 mm/page_alloc.c:1251
 free_compound_page+0x8b/0xc0 mm/page_alloc.c:571
 free_transhuge_page+0x3bc/0x470 mm/huge_memory.c:2729
 __put_compound_page mm/swap.c:96 [inline]
 release_pages+0x73c/0x16f0 mm/swap.c:760
 free_pages_and_swap_cache+0x57b/0x5b0 mm/swap_state.c:319
 tlb_flush_mmu_free mm/memory.c:260 [inline]
 tlb_flush_mmu mm/memory.c:269 [inline]
 arch_tlb_finish_mmu mm/memory.c:284 [inline]
 tlb_finish_mmu+0x290/0x5c0 mm/memory.c:434
 zap_page_range+0xb42/0xbf0 mm/memory.c:1622
 madvise_dontneed_single_vma mm/madvise.c:510 [inline]
 madvise_dontneed_free mm/madvise.c:563 [inline]
 madvise_vma mm/madvise.c:688 [inline]
 __do_sys_madvise mm/madvise.c:863 [inline]
 __se_sys_madvise+0x1922/0x3b20 mm/madvise.c:791
 __x64_sys_madvise+0xd8/0x110 mm/madvise.c:791
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x45ddc7
Code: 8b 24 24 48 8b 6c 24 10 48 83 c4 18 c3 cc cc cc cc cc cc 48 8b 7c 24 08 48 8b 74 24 10 8b 54 24 18 48 c7 c0 1c 00 00 00 0f 05 <c3> cc cc cc cc cc cc cc cc 48 8b 7c 24 08 8b 74 24 10 8b 54 24 14 
RSP: 002b:00007ffc605de758 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 0000000000e58000 RCX: 000000000045ddc7
RDX: 0000000000000004 RSI: 0000000000e58000 RDI: 000000c42d254000
RBP: 00007ffc605de788 R08: 000000c430012000 R09: 0000000000001000
R10: 00000000000d8000 R11: 0000000000000246 R12: 0000000000001b30
R13: 00000000000000fc R14: 00007f99ac1d66c8 R15: 0000000000000080
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
CR2: 0000000000000050
---[ end trace f4bc946cb9f1f8e5 ]---
RIP: 0010:kmsan_free_page+0xfc/0x2f0 mm/kmsan/kmsan_hooks.c:318
Code: 01 00 00 48 c7 00 00 00 00 00 44 39 e1 0f 8d b0 00 00 00 48 63 d1 48 8d 14 52 48 c1 e2 05 48 8b 54 13 40 48 83 c0 60 83 c1 01 <80> 7a 50 00 74 be 0f 0b 66 90 66 2e 0f 1f 84 00 00 00 00 00 eb fe 
RSP: 0018:ffff880197c9f5d8 EFLAGS: 00010002
RAX: ffffea000220abc8 RBX: ffffea0002208000 RCX: 0000000000000075
RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffffea00078e4000
RBP: ffff880197c9f628 R08: 0000000000480020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff81c6d720 R12: 0000000000000200
R13: ffff8801d0768000 R14: 0000000000000009 R15: ffffea0000624000
FS:  000000000234e628(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000050 CR3: 00000001abd70000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600