Re: [PATCH] scsi: ses: Handle enclosure with just a primary component gracefully

[Ding Hui]

On 2023/4/5 4:26, James Bottomley wrote:
> On Tue, 2023-04-04 at 21:23 +0200, Jiri Kosina wrote:
> > From: Jiri Kosina <jkosina@xxxxxxx>
> >
> > This reverts 3fe97ff3d9493 ("scsi: ses: Don't attach if enclosure has
> > no components") and introduces proper handling of case where there
> > are no detected secondary components, but primary component
> > (enumerated in num_enclosures) does exist. That fix was originally
> > proposed by Ding Hui <dinghui@xxxxxxxxxxxxxx>.
>
> I think everything in here looks fine except this:
>
> > --- a/drivers/scsi/ses.c
> > +++ b/drivers/scsi/ses.c
> > @@ -509,9 +509,6 @@ static int ses_enclosure_find_by_addr(struct
> > enclosure_device *edev,
> >          int i;
> >          struct ses_component *scomp;
> >   
> > -       if (!edev->component[0].scratch)
> > -               return 0;
> > -
> >          for (i = 0; i < edev->components; i++) {
> >                  scomp = edev->component[i].scratch;
> >                  if (scomp->addr != efd->addr)
>
> If you remove the check, then scomp could be NULL here and we'll oops
> on scomp->addr.

I think we should remove the check, because the edev->components 
represented the effectiveness of array pointers, so we need check 
edev->components firstly instead of checking edev->component[0].scratch, 
if edev->components is 0, we won't enter the for loop, don't worry about 
dereference scomp.

> Regards,
>
> James

--
Thanks,
-dinghui