linux-kernel - Re: [PATCH v2] powerpc: kernel: fix refcount leak in format

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Date:   Mon, 7 Mar 2022 10:52:25 +0800
From:   Hangyu Hua <hbh25y@...il.com>
To:     mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        tyreld@...ux.ibm.com
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] powerpc: kernel: fix refcount leak in format_show()

Any further suggestions for this patch? guys.

Thanks.

On 2022/3/2 10:19, Hangyu Hua wrote:
> Refcount leak will happen when format_show returns failure in multiple
> cases. Unified management of of_node_put can fix this problem.
> 
> Signed-off-by: Hangyu Hua <hbh25y@...il.com>
> ---
> 
> v2:
> 1. change the title and description information.
> 2. fix all possible refcount leak.
> 
>   arch/powerpc/kernel/secvar-sysfs.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
> index a0a78aba2083..1ee4640a2641 100644
> --- a/arch/powerpc/kernel/secvar-sysfs.c
> +++ b/arch/powerpc/kernel/secvar-sysfs.c
> @@ -26,15 +26,18 @@ static ssize_t format_show(struct kobject *kobj, struct kobj_attribute *attr,
>   	const char *format;
>   
>   	node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
> -	if (!of_device_is_available(node))
> -		return -ENODEV;
> +	if (!of_device_is_available(node)) {
> +		rc = -ENODEV;
> +		goto out;
> +	}
>   
>   	rc = of_property_read_string(node, "format", &format);
>   	if (rc)
> -		return rc;
> +		goto out;
>   
>   	rc = sprintf(buf, "%s\n", format);
>   
> +out:
>   	of_node_put(node);
>   
>   	return rc;