syzbot has bisected this issue to:

commit 9fd75b66b8f68498454d685dc4ba13192ae069b0
Author: Duoming Zhou [off-list ref]
Date:   Fri Mar 18 00:54:04 2022 +0000

    ax25: Fix refcount leaks caused by ax25_cb_del()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12f83301980000
start commit:   568ebdaba637 MAINTAINERS: adjust file entry in FREESCALE Q..
git tree:       net-next
final oops:     https://syzkaller.appspot.com/x/report.txt?x=11f83301980000
console output: https://syzkaller.appspot.com/x/log.txt?x=16f83301980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
dashboard link: https://syzkaller.appspot.com/bug?extid=33841dc6aa3e1d86b78a
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=121324ae980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1607cdda980000

Reported-by: syzbot+33841dc6aa3e1d86b78a@syzkaller.appspotmail.com
Fixes: 9fd75b66b8f6 ("ax25: Fix refcount leaks caused by ax25_cb_del()")

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