BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 122214067 P4D 122214067 PUD 121e03067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 0 PID: 48 Comm: kworker/u4:3 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_dat_purge
RIP: 0010:arpt_do_table+0x1dd/0xd40 net/ipv4/netfilter/arp_tables.c:209
Code: 40 e8 f7 63 57 fd 49 8d 7e 38 4c 89 64 24 30 4f 8d 3c ae 89 c5 e8 63 2d 26 fc 49 8b 46 38 48 8d 2c e8 48 89 ef e8 53 2d 26 fc <48> 8b 45 00 49 8d 7f 0c 4c 89 f5 4c 89 7c 24 68 48 89 44 24 48 e8
RSP: 0018:ffffc90000003c10 EFLAGS: 00010246
RAX: ffff88812c0295a0 RBX: ffffc90000003d90 RCX: ffffffff88af0358
RDX: 00000000000003ea RSI: ffffffff8285fdfa RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 00008880a5d0426f R11: 0000000000000007 R12: ffff8880a20c3440
R13: 0000000000000000 R14: ffff8880a20c3400 R15: ffff8880a20c3400
FS:  0000000000000000(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000011e282000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 arptable_filter_hook+0x44/0x60 net/ipv4/netfilter/arptable_filter.c:37
 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
 nf_hook_slow+0x7c/0x160 net/netfilter/core.c:512
 nf_hook include/linux/netfilter.h:262 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 arp_rcv net/ipv4/arp.c:961 [inline]
 arp_rcv+0x38b/0x430 net/ipv4/arp.c:936
 __netif_receive_skb_one_core+0x9f/0xe0 net/core/dev.c:5187
 __netif_receive_skb+0x33/0xf0 net/core/dev.c:5301
 process_backlog+0x213/0x4c0 net/core/dev.c:6133
 napi_poll net/core/dev.c:6571 [inline]
 net_rx_action+0x3ad/0xac0 net/core/dev.c:6639
 __do_softirq+0x118/0x34a kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1082
 </IRQ>
 do_softirq.part.0+0x66/0x70 kernel/softirq.c:337
 do_softirq kernel/softirq.c:329 [inline]
 __local_bh_enable_ip+0x70/0x80 kernel/softirq.c:189
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:176 [inline]
 _raw_spin_unlock_bh+0x3d/0x50 kernel/locking/spinlock.c:207
 spin_unlock_bh include/linux/spinlock.h:398 [inline]
 __batadv_dat_purge.isra.0.part.0+0x1e1/0x250 net/batman-adv/distributed-arp-table.c:185
 __batadv_dat_purge net/batman-adv/distributed-arp-table.c:166 [inline]
 batadv_dat_purge+0x44/0x60 net/batman-adv/distributed-arp-table.c:204
 process_one_work+0x424/0x930 kernel/workqueue.c:2268
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2414
 kthread+0x203/0x230 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
CR2: 0000000000000000
---[ end trace 72434c17f11f7b44 ]---
RIP: 0010:arpt_do_table+0x1dd/0xd40 net/ipv4/netfilter/arp_tables.c:209
Code: 40 e8 f7 63 57 fd 49 8d 7e 38 4c 89 64 24 30 4f 8d 3c ae 89 c5 e8 63 2d 26 fc 49 8b 46 38 48 8d 2c e8 48 89 ef e8 53 2d 26 fc <48> 8b 45 00 49 8d 7f 0c 4c 89 f5 4c 89 7c 24 68 48 89 44 24 48 e8
RSP: 0018:ffffc90000003c10 EFLAGS: 00010246
RAX: ffff88812c0295a0 RBX: ffffc90000003d90 RCX: ffffffff88af0358
RDX: 00000000000003ea RSI: ffffffff8285fdfa RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 00008880a5d0426f R11: 0000000000000007 R12: ffff8880a20c3440
R13: 0000000000000000 R14: ffff8880a20c3400 R15: ffff8880a20c3400
FS:  0000000000000000(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000011e282000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400