syzbot has bisected this bug to:

commit 84a4062632462c4320704fcdf8e99e89e94c0aba
Author: Johan Korsnes [off-list ref]
Date:   Fri Jan 17 12:08:36 2020 +0000

    HID: core: increase HID report buffer size to 8KiB

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=113098b1e00000
start commit:   2c523b34 Linux 5.6-rc5
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=133098b1e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=153098b1e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a5295e161cd85b82
dashboard link: https://syzkaller.appspot.com/bug?extid=8357fbef0d7bb602de45
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11b439c3e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16dc6fb5e00000

Reported-by: syzbot+8357fbef0d7bb602de45@syzkaller.appspotmail.com
Fixes: 84a406263246 ("HID: core: increase HID report buffer size to 8KiB")

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