nf_conntrack: default automatic helper assignment has been turned off for security reasons and CT-based  firewall rule not found. Use the iptables CT target to attach helpers instead.
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 8964 Comm: syz-executor611 Not tainted 5.4.0-next-20191207-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__write_once_size include/linux/compiler.h:247 [inline]
RIP: 0010:__skb_unlink include/linux/skbuff.h:2026 [inline]
RIP: 0010:skb_unlink+0xc4/0x160 net/core/skbuff.c:3165
Code: 00 00 49 8d 7d 08 4c 8b 63 08 48 b8 00 00 00 00 00 fc ff df 48 c7 43 08 00 00 00 00 48 89 fa 48 c7 03 00 00 00 00 48 c1 ea 03 <80> 3c 02 00 75 58 4c 89 e2 4d 89 65 08 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc90001e07880 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: ffff8880a4804940 RCX: ffffffff815bf9f9
RDX: 0000000000000001 RSI: 0000000000000286 RDI: 0000000000000008
RBP: ffffc90001e078a8 R08: 0000000000000004 R09: fffff520003c0efd
R10: fffff520003c0efc R11: 0000000000000003 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880a30819e8 R15: ffffc90001e07950
FS:  00007f1c941d9700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000209ff000 CR3: 00000000a953f000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 kcm_recvmsg+0x462/0x560 net/kcm/kcmsock.c:1161
 sock_recvmsg_nosec+0x89/0xb0 net/socket.c:873
 ____sys_recvmsg+0x236/0x550 net/socket.c:2549
 ___sys_recvmsg+0xe4/0x150 net/socket.c:2590
 do_recvmmsg+0x27e/0x7a0 net/socket.c:2688
 __sys_recvmmsg+0x259/0x270 net/socket.c:2767
 __do_sys_recvmmsg net/socket.c:2790 [inline]
 __se_sys_recvmmsg net/socket.c:2783 [inline]
 __x64_sys_recvmmsg+0xe6/0x140 net/socket.c:2783
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446a69
Code: e8 5c b3 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1c941d8d98 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 0000000000446a69
RDX: 0400000000000310 RSI: 0000000020003540 RDI: 0000000000000005
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00000000002b0095 R14: 0000a50000000000 R15: 0000000300000018
Modules linked in:
---[ end trace 2e0d807b6e384251 ]---
RIP: 0010:__write_once_size include/linux/compiler.h:247 [inline]
RIP: 0010:__skb_unlink include/linux/skbuff.h:2026 [inline]
RIP: 0010:skb_unlink+0xc4/0x160 net/core/skbuff.c:3165
Code: 00 00 49 8d 7d 08 4c 8b 63 08 48 b8 00 00 00 00 00 fc ff df 48 c7 43 08 00 00 00 00 48 89 fa 48 c7 03 00 00 00 00 48 c1 ea 03 <80> 3c 02 00 75 58 4c 89 e2 4d 89 65 08 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc90001e07880 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: ffff8880a4804940 RCX: ffffffff815bf9f9
RDX: 0000000000000001 RSI: 0000000000000286 RDI: 0000000000000008
RBP: ffffc90001e078a8 R08: 0000000000000004 R09: fffff520003c0efd
R10: fffff520003c0efc R11: 0000000000000003 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880a30819e8 R15: ffffc90001e07950
FS:  00007f1c941d9700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000209ff000 CR3: 00000000a953f000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400