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Date:   Thu, 1 Oct 2020 15:35:46 +0200
From:   David Sterba <dsterba@suse.cz>
To:     Dmitry Vyukov <dvyukov@google.com>
Cc:     dsterba@suse.cz,
        syzbot <syzbot+582e66e5edf36a22c7b0@syzkaller.appspotmail.com>,
        Chris Mason <clm@fb.com>, dsterba@suse.com,
        Josef Bacik <josef@toxicpanda.com>,
        linux-btrfs@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: KASAN: use-after-free Read in btrfs_scan_one_device
Message-ID: <20201001133546.GV6756@twin.jikos.cz>
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        Josef Bacik <josef@toxicpanda.com>, linux-btrfs@vger.kernel.org,
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On Thu, Oct 01, 2020 at 03:08:34PM +0200, Dmitry Vyukov wrote:
> On Thu, Oct 1, 2020 at 3:05 PM Dmitry Vyukov <dvyukov@google.com> wrote:
> >
> > On Wed, Sep 30, 2020 at 8:06 PM David Sterba <dsterba@suse.cz> wrote:
> > >
> > > On Wed, Sep 30, 2020 at 06:57:56PM +0200, David Sterba wrote:
> > > > On Sun, Sep 20, 2020 at 07:12:14AM -0700, syzbot wrote:
> > > > > Hello,
> > > > >
> > > > > syzbot found the following issue on:
> > > > >
> > > > > HEAD commit:    eb5f95f1 Merge tag 's390-5.9-6' of git://git.kernel.org/pu..
> > > > > git tree:       upstream
> > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=10a0a8bb900000
> > > > > kernel config:  https://syzkaller.appspot.com/x/.config?x=ffe85b197a57c180
> > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=582e66e5edf36a22c7b0
> > > > > compiler:       gcc (GCC) 10.1.0-syz 20200507
> > > > >
> > > > > Unfortunately, I don't have any reproducer for this issue yet.
> > > > >
> > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > > > Reported-by: syzbot+582e66e5edf36a22c7b0@syzkaller.appspotmail.com
> > > >
> > > > #syz fix: btrfs: fix overflow when copying corrupt csums for a message
> > >
> > > Johannes spotted that this is not the right fix for this report, I don't
> > > know how to tell syzbot to revert the 'fix:' command, there isn't
> > > 'unfix' (like there's 'undup').
> >
> > Hi David,
> >
> > I've added "unfix" command:
> > https://github.com/google/syzkaller/pull/2156
> >
> > Let's give it a try:
> > #syz unfix
> >
> > Thanks
> 
> Voil?! Unfixed:
> https://syzkaller.appspot.com/bug?extid=582e66e5edf36a22c7b0

Thanks!