Re: [PATCH 2/2] fsnotify: Protect bail out path of fsnotify_add_mark_locked() properly

[Jan Kara <jack@suse.cz>]

On Tue 31-10-17 14:26:35, Amir Goldstein wrote:
> On Tue, Oct 31, 2017 at 11:33 AM, Jan Kara <jack@suse.cz> wrote:
> > When fsnotify_add_mark_locked() fails it cleans up the mark it was
> > adding. Since the mark is already visible in group's list, we should
> > protect update of mark->flags with mark->lock. I'm not aware of any real
> > issues this could cause (since we also hold group->mark_mutex) but
> > better be safe and obey locking rules properly.
> >
> > Signed-off-by: Jan Kara <jack@suse.cz>
> 
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> 
> IMO, even though this does not fix a concrete bug, if it's worth
> fixing in upstream, it's worth fixing in stable.
> A future stable fix may either make this into a concrete bug
> or just be harder to apply.
> 
> So I suggest to add the Fixes: and Cc: stable tags.
> 
> Greg,
> 
> Do you agree with this reasoning?

Similarly as with patch 1, I don't think real users can hit this (and even
if they could, I doubt it would have any negative impact). So bothering
stable with this is just a waste of resources... It falls under the
"theoretical race condition" cathegory which is explicitely forbidden from
stable.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR