Re: [PATCH AUTOSEL 4.19 33/57] blk-mq: protect debugfs_create_files() from failures

[Sasha Levin]

On Sat, Mar 30, 2019 at 06:43:11AM +0100, Greg Kroah-Hartman wrote:
> On Fri, Mar 29, 2019 at 09:28:26PM -0400, Sasha Levin wrote:
> > From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> >
> > [ Upstream commit 36991ca68db9dd43bac7f3519f080ee3939263ef ]
> >
> > If debugfs were to return a non-NULL error for a debugfs call, using
> > that pointer later in debugfs_create_files() would crash.
> >
> > Fix that by properly checking the pointer before referencing it.
> >
> > Reported-by: Michal Hocko <mhocko@xxxxxxxxxx>
> > Reported-and-tested-by: syzbot+b382ba6a802a3d242790@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
> >  block/blk-mq-debugfs.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> > index cb1e6cf7ac48..9dc3a0896462 100644
> > --- a/block/blk-mq-debugfs.c
> > +++ b/block/blk-mq-debugfs.c
> > @@ -806,6 +806,9 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {
> >  static bool debugfs_create_files(struct dentry *parent, void *data,
> >  				 const struct blk_mq_debugfs_attr *attr)
> >  {
> > +	if (IS_ERR_OR_NULL(parent))
> > +		return false;
> > +
> >  	d_inode(parent)->i_private = data;
> >
> >  	for (; attr->name; attr++) {
> > --
> > 2.19.1
>
> This was a 5.0-only thing, no need for it to be backported anywhere.
> Please drop it from all of your trees.

Dropped, thanks.

--
Thanks,
Sasha