[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAJfpeguB7v8OBAuJoiPKv6FbfXP6wV2H8a9ceUUuPk4Aca3NRA@mail.gmail.com>
Date: Mon, 2 Mar 2020 12:17:34 +0100
From: Miklos Szeredi <miklos@...redi.hu>
To: Amir Goldstein <amir73il@...il.com>
Cc: syzbot <syzbot+66a9752fa927f745385e@...kaller.appspotmail.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
linux-kernel <linux-kernel@...r.kernel.org>,
overlayfs <linux-unionfs@...r.kernel.org>,
Miklos Szeredi <mszeredi@...hat.com>,
syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: WARNING: bad unlock balance in ovl_llseek
On Mon, Mar 2, 2020 at 12:10 PM Amir Goldstein <amir73il@...il.com> wrote:
> > =====================================
> > WARNING: bad unlock balance detected!
> > 5.6.0-rc3-syzkaller #0 Not tainted
> > -------------------------------------
> > syz-executor194/8947 is trying to release lock (&ovl_i_lock_key[depth]) at:
> > [<ffffffff828b7835>] ovl_inode_unlock fs/overlayfs/overlayfs.h:328 [inline]
> > [<ffffffff828b7835>] ovl_llseek+0x215/0x2c0 fs/overlayfs/file.c:193
> > but there are no more locks to release!
> >
>
> This is strange. I don't see how that can happen nor how my change would
> have caused this regression. If anything, the lock chance may have brought
> a bug in stack file ops to light, but don't see the bug.
The bug is that ovl_inode_lock() is interruptible and that the caller
doesn't check for error.
I think the fix is to make this lock uninterruptible (probably rename
the current helper to _interruptible and use the current name as the
uninterruptible version).
Thanks,
Miklos
Powered by blists - more mailing lists