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SubjectRe: WARNING in __kernel_read (2)
On Sat, Sep 26, 2020 at 01:17:04PM +0000, David Laight wrote:
> From: David Laight
> > Sent: 26 September 2020 12:16
> > To: 'syzbot' <syzbot+51177e4144d764827c45@syzkaller.appspotmail.com>; linux-fsdevel@vger.kernel.org;
> > linux-kernel@vger.kernel.org; syzkaller-bugs@googlegroups.com; viro@zeniv.linux.org.uk
> > Subject: RE: WARNING in __kernel_read (2)
> >
> > > From: syzbot <syzbot+51177e4144d764827c45@syzkaller.appspotmail.com>
> > > Sent: 26 September 2020 03:58
> > > To: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; syzkaller-bugs@googlegroups.com;
> > > viro@zeniv.linux.org.uk
> > > Subject: WARNING in __kernel_read (2)
> >
> > I suspect this is calling finit_module() on an fd
> > that doesn't have read permissions.
>
> Code inspection also seems to imply that the check means
> the exec() also requires read permissions on the file.
>
> This isn't traditionally true.
> suid #! scripts are particularly odd without 'owner read'
> (everyone except the owner can run them!).

Christoph, any thoughts here? You added this WARN_ON_ONCE in:

commit 61a707c543e2afe3aa7e88f87267c5dafa4b5afa
Author: Christoph Hellwig <hch@lst.de>
Date: Fri May 8 08:54:16 2020 +0200

fs: add a __kernel_read helper

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