syzbot has bisected this issue to:

commit b9df4fd7e99cb8bfd80c4143f3045d63b1754ad0
Author: Heiner Kallweit [off-list ref]
Date:   Sun Oct 6 16:19:54 2019 +0000

    net: core: change return type of pskb_may_pull to bool

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11b4545cd00000
start commit:   1048ba83 Linux 5.11-rc6
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=13b4545cd00000
console output: https://syzkaller.appspot.com/x/log.txt?x=15b4545cd00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3ae5569643a9955f
dashboard link: https://syzkaller.appspot.com/bug?extid=105896fac213f26056f9
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16f0e564d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=147075e8d00000

Reported-by: syzbot+105896fac213f26056f9@syzkaller.appspotmail.com
Fixes: b9df4fd7e99c ("net: core: change return type of pskb_may_pull to bool")

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