[PATCH v4] powerpc/powernv: add NULL check after kzalloc in opal_add_one_export

[PATCH v4] powerpc/powernv: add NULL check after kzalloc in opal_add_one_export

[Qiujun Huang]

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@gmail.com>
Reviewed-by: Oliver O'Halloran <oohall@gmail.com>

---

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

Re: [PATCH v4] powerpc/powernv: add NULL check after kzalloc in opal_add_one_export

[Michael Ellerman]

Qiujun Huang <hqjagain@gmail.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@gmail.com>
> Reviewed-by: Oliver O'Halloran <oohall@gmail.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.

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

Re: [PATCH v4] powerpc/powernv: add NULL check after kzalloc in opal_add_one_export

[Qiujun Huang]

On Mon, Apr 6, 2020 at 6:30 PM Michael Ellerman <mpe@ellerman.id.au> wrote:
>
> Qiujun Huang <hqjagain@gmail.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@gmail.com>
> > Reviewed-by: Oliver O'Halloran <oohall@gmail.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

Re: [PATCH v4] powerpc/powernv: add NULL check after kzalloc in opal_add_one_export

[Markus Elfring]

>>> Here needs a NULL check as kzalloc may fail returning NULL.

I find this wording potentially confusing.

* Such function calls will usually succeed to return a pointer.

* The desired memory allocation can fail.

* Please choose an imperative wording for the change description.


>>> Issue was found by coccinelle.

Please omit this line after the addition for the reference to the SmPL script.


>>> Generated by: scripts/coccinelle/null/kmerr.cocci
…
>>> Reviewed-by: Oliver O'Halloran <oohall@gmail.com>

I wonder about this tag because of requested changes for the shown patch approach.

I recommend to add the tag “Fixes”.


>> Thanks for putting up with all the review comments :)

This seems to become challenging here.


>> But I think this should actually be two patches now.
…

> Get that, I'll separate them.

I wonder why it was not directly tried in this patch version.


>>> v3->v4:

I suggest to apply a shorter version numbering format (without an arrow).

Regards,
Markus