Re: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow

[Dmitry Vyukov]

On Sat, Jan 9, 2021 at 8:20 AM syzbot
<syzbot+3db80bbf66b88d68af9d@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> syzbot suspects this issue was fixed by commit:
>
> commit d24396c5290ba8ab04ba505176874c4e04a2d53c
> Author: Rustam Kovhaev <rkovhaev@xxxxxxxxx>
> Date:   Sun Nov 1 14:09:58 2020 +0000
>
>     reiserfs: add check for an invalid ih_entry_count
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=111480e7500000
> start commit:   a68a0262 mm/madvise: remove racy mm ownership check
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e597c2b53c984cd8
> dashboard link: https://syzkaller.appspot.com/bug?extid=3db80bbf66b88d68af9d
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1737b8a7500000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1697246b500000
>
> If the result looks correct, please mark the issue as fixed by replying with:
>
> #syz fix: reiserfs: add check for an invalid ih_entry_count
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Looks realistic.

#syz fix: reiserfs: add check for an invalid ih_entry_count