Re: KASAN: null-ptr-deref Write in io_wq_cancel_all

[syzbot]

syzbot has bisected this bug to:

commit d5f773aba1186142d52aef8242a426310a39fa86
Author: Jens Axboe <axboe@xxxxxxxxx>
Date:   Thu Oct 24 13:25:42 2019 +0000

    io_uring: replace workqueue usage with io-wq

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=142c6d18e00000
start commit:   139c2d13 Add linux-next specific files for 20191025
git tree:       linux-next
final crash:    https://syzkaller.appspot.com/x/report.txt?x=162c6d18e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=122c6d18e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=28fd7a693df38d29
dashboard link: https://syzkaller.appspot.com/bug?extid=d958a65633ea70280b23
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=160573c0e00000

Reported-by: syzbot+d958a65633ea70280b23@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: d5f773aba118 ("io_uring: replace workqueue usage with io-wq")

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