Re: general protection fault in do_move_mount

[Al Viro]

On Thu, May 09, 2019 at 07:30:34AM +0100, Al Viro wrote:
> On Wed, May 08, 2019 at 10:40:06PM -0700, syzbot wrote:
> > Hello,
> > 
> > syzbot found the following crash on:
> > 
> > HEAD commit:    80f23212 Merge git://git.kernel.org/pub/scm/linux/kernel/g..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=11ab8dd0a00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=40a58b399941db7e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=494c7ddf66acac0ad747
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > 
> > Unfortunately, I don't have any reproducer for this crash yet.
> > 
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+494c7ddf66acac0ad747@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> *Ugh*
> 
> That's a bloody dumb leftover from very old variant of that thing;
> the following should fix it.

In vfs.git#fixes, will send a pull request tomorrow...