linux-kernel - Re: [syzbot] Monthly fuse report

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Date:   Fri, 14 Apr 2023 17:09:42 +0200
From:   Aleksandr Nogikh <nogikh@...gle.com>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        syzbot <syzbot+list69b50efce6f847334104@...kaller.appspotmail.com>
Subject: Re: [syzbot] Monthly fuse report

On Wed, Apr 12, 2023 at 3:52 PM 'Miklos Szeredi' via syzkaller-bugs
<syzkaller-bugs@...glegroups.com> wrote:
>
> On Wed, 5 Apr 2023 at 11:00, syzbot
> <syzbot+list69b50efce6f847334104@...kaller.appspotmail.com> wrote:
> >
> > Hello fuse maintainers/developers,
> >
> > This is a 30-day syzbot report for the fuse subsystem.
> > All related reports/information can be found at:
> > https://syzkaller.appspot.com/upstream/s/fuse
> >
> > During the period, 0 new issues were detected and 0 were fixed.
> > In total, 8 issues are still open and 34 have been fixed so far.
> >
> > Some of the still happening issues:
> >
> > Crashes Repro Title
> > 146     Yes   INFO: task hung in fuse_simple_request
> >               https://syzkaller.appspot.com/bug?extid=46fe899420456e014d6b
> > 26      Yes   INFO: task hung in lookup_slow (3)
> >               https://syzkaller.appspot.com/bug?extid=7cfc6a4f6b025f710423
> > 13      Yes   INFO: task hung in walk_component (5)
> >               https://syzkaller.appspot.com/bug?extid=8fba0e0286621ce71edd
>
> Hi Dmitry,
>
> These all look like non-kernel deadlocks.
>
> AFAIR syzbot was taught about breaking these by "umount -f" or "echo 1
> > /sys/fs/fuse/connections/$DEV/abort", right?

Hi Miklos,

syzbot indeed writes 0x1 to each /sys/fs/fuse/connections/%s/abort
See https://github.com/google/syzkaller/blob/ec410564b9e4ff241d1242febb29eda2ee28b50d/executor/common_linux.h#L4614

Some C reproducers (e.g.
https://syzkaller.appspot.com/text?tag=ReproC&x=128284a0b00000) also
contain that piece of code.

--
Aleksandr

>
> I wonder why they are still triggering a report then.
>
> Thanks,
> Miklos
>
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