syzbot suspects this bug was fixed by commit:

commit 32c72165dbd0e246e69d16a3ad348a4851afd415 Author: Kadlecsik József kadlec@blackhole.kfki.hu Date: Sun Jan 19 21:06:49 2020 +0000

netfilter: ipset: use bitmap infrastructure completely

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10aef753e00000 start commit: 4703d911 Merge tag 'xarray-5.5' of git://git.infradead.org.. git tree: upstream kernel config: https://syzkaller.appspot.com/x/.config?x=83c00afca9cf5153 dashboard link: https://syzkaller.appspot.com/bug?extid=a85062dec5d65617cc1c syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1301ed85e00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b7b79ee00000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: netfilter: ipset: use bitmap infrastructure completely

For information about bisection process see: https://goo.gl/tpsmEJ#bisection