syzbot has bisected this issue to:

commit 2030043e616cab40f510299f09b636285e0a3678
Author: Oleksij Rempel [off-list ref]
Date:   Fri May 21 11:57:20 2021 +0000

    can: j1939: fix Use-after-Free, hold skb ref while in use

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1438c947680000
start commit:   1b907d050735 Merge tag '6.7-rc-smb3-client-fixes-part2' of..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1638c947680000
console output: https://syzkaller.appspot.com/x/log.txt?x=1238c947680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=88e7ba51eecd9cd6
dashboard link: https://syzkaller.appspot.com/bug?extid=1591462f226d9cbf0564
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17fea8fb680000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1633dc70e80000

Reported-by: syzbot+1591462f226d9cbf0564@syzkaller.appspotmail.com
Fixes: 2030043e616c ("can: j1939: fix Use-after-Free, hold skb ref while in use")

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