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

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Message-ID: <87eet0sy79.fsf@mpe.ellerman.id.au>
Date:   Mon, 06 Apr 2020 20:30:50 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Qiujun Huang <hqjagain@...il.com>, benh@...nel.crashing.org,
        paulus@...ba.org, oohall@...il.com
Cc:     tglx@...utronix.de, Markus.Elfring@....de, christophe.leroy@....fr,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Qiujun Huang <hqjagain@...il.com>
Subject: Re: [PATCH v4] powerpc/powernv: add NULL check after kzalloc in opal_add_one_export

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.

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