[syzbot] [fs?] KASAN: slab-use-after-free Read in __fput (2)

[syzbot]

syzbot has bisected this issue to:

commit ff2d23843f7fb4f13055be5a4a9a20ddd04e6e9c
Author: Michel Dänzer <mdaenzer at redhat.com>
Date:   Fri Jul 23 07:58:57 2021 +0000

    dma-buf/poll: Get a file reference for outstanding fence callbacks

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17c1007c980000
start commit:   5eb4573ea63d Merge tag 'soc-fixes-6.9-2' of git://git.kern..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1421007c980000
console output: https://syzkaller.appspot.com/x/log.txt?x=1021007c980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9d985095f83428be
dashboard link: https://syzkaller.appspot.com/bug?extid=5d4cb6b4409edfd18646
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11a13cf8980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15c4d2f8980000

Reported-by: syzbot+5d4cb6b4409edfd18646 at syzkaller.appspotmail.com
Fixes: ff2d23843f7f ("dma-buf/poll: Get a file reference for outstanding fence callbacks")

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