KASAN: null-ptr-deref Read in refcount_inc_not_zero

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BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
BUG: KASAN: null-ptr-deref in refcount_inc_not_zero_checked+0x81/0x200 lib/refcount.c:123
Read of size 4 at addr 000000000000004a by task syz-executor.2/29310

CPU: 1 PID: 29310 Comm: syz-executor.2 Not tainted 5.2.0-rc2+ #36
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 __kasan_report.cold+0x5/0x40 mm/kasan/report.c:321
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 kasan_check_read+0x11/0x20 mm/kasan/common.c:94
 atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
 refcount_inc_not_zero_checked+0x81/0x200 lib/refcount.c:123
 ipv4_neigh_lookup+0x44e/0x1590 net/ipv4/route.c:454
 dst_neigh_lookup_skb include/net/dst.h:401 [inline]
 __neigh_update+0xba7/0x2570 net/core/neighbour.c:1383
 neigh_update+0x37/0x50 net/core/neighbour.c:1416
 arp_req_set+0x2e7/0x720 net/ipv4/arp.c:1072
 arp_ioctl+0x652/0x7f0 net/ipv4/arp.c:1230
 inet_ioctl+0x2a0/0x340 net/ipv4/af_inet.c:930
 sock_do_ioctl+0xd8/0x2f0 net/socket.c:1049
 sock_ioctl+0x3ed/0x780 net/socket.c:1200
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459279
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1974a3fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459279
RDX: 0000000020000240 RSI: 0000000000008955 RDI: 0000000000000006
RBP: 000000000075bfc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1974a406d4
R13: 00000000004c4c41 R14: 00000000004d8958 R15: 00000000ffffffff
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