linux-kernel - Re: [PATCH v4] powerpc/powernv: add NULL check after kzalloc in opal_add_one

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Message-ID: <CAJRQjoeTYg6NnxwvXusU6fdOFOmOiceokYJZQ23-0YQo_yqZ5w@mail.gmail.com>
Date:   Mon, 6 Apr 2020 18:43:27 +0800
From:   Qiujun Huang <hqjagain@...il.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        "Oliver O'Halloran" <oohall@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Markus Elfring <Markus.Elfring@....de>,
        Christophe Leroy <christophe.leroy@....fr>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] powerpc/powernv: add NULL check after kzalloc in opal_add_one_export

On Mon, Apr 6, 2020 at 6:30 PM Michael Ellerman <mpe@...erman.id.au> wrote:
>
> Qiujun Huang <hqjagain@...il.com> writes:
> > Here needs a NULL check as kzalloc may fail returning NULL.
> >
> > Issue was found by coccinelle.
> > Generated by: scripts/coccinelle/null/kmerr.cocci
> >
> > Signed-off-by: Qiujun Huang <hqjagain@...il.com>
> > Reviewed-by: Oliver O'Halloran <oohall@...il.com>
> >
> > ---
>
> Thanks for putting up with all the review comments :)
>
> But I think this should actually be two patches now.
>
> The first patch should change the goto after
> of_property_read_u64_array() into a return and drop the redundant
> assignments.
>
> Then the second patch can add the NULL check for attr.

Get that, I'll separate them.

>
> cheers
>
> > v3->v4:
> >       Added the information about coccinelle script.
> >       Added change log.
> >       Added Oliver's Reviewed-by.
> > v2->v3:
> >       Removed redundant assignment to 'attr' and 'name'.
> > v1->v2:
> >       Just return -ENOMEM if attr is NULL.
> > ---
> >  arch/powerpc/platforms/powernv/opal.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> > index 2b3dfd0b6cdd..908d749bcef5 100644
> > --- a/arch/powerpc/platforms/powernv/opal.c
> > +++ b/arch/powerpc/platforms/powernv/opal.c
> > @@ -801,16 +801,19 @@ static ssize_t export_attr_read(struct file *fp, struct kobject *kobj,
> >  static int opal_add_one_export(struct kobject *parent, const char *export_name,
> >                              struct device_node *np, const char *prop_name)
> >  {
> > -     struct bin_attribute *attr = NULL;
> > -     const char *name = NULL;
> > +     struct bin_attribute *attr;
> > +     const char *name;
> >       u64 vals[2];
> >       int rc;
> >
> >       rc = of_property_read_u64_array(np, prop_name, &vals[0], 2);
> >       if (rc)
> > -             goto out;
> > +             return rc;
> >
> >       attr = kzalloc(sizeof(*attr), GFP_KERNEL);
> > +     if (!attr)
> > +             return -ENOMEM;
> > +
> >       name = kstrdup(export_name, GFP_KERNEL);
> >       if (!name) {
> >               rc = -ENOMEM;
> > --
> > 2.17.1