linux-kernel - Re: [PATCH v1] device property: Avoid NULL pointer dereference in device_get_next_child

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Date:   Fri, 17 Jul 2020 17:05:25 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] device property: Avoid NULL pointer dereference in
 device_get_next_child_node()

On Thu, 2020-07-16 at 21:27 +0300, Andy Shevchenko wrote:
> When we have no primary fwnode or when it's a software node, we may end up
> in the situation when fwnode is a NULL pointer. There is no point to look for
> secondary fwnode in such case. Add a necessary check to a condition.
> 
> Fixes: 114dbb4fa7c4 ("drivers property: When no children in primary, try secondary")
> Reported-by: Maxim Levitsky <mlevitsk@...hat.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

Tested-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky

> ---
>  drivers/base/property.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index 1e6d75e65938..d58aa98fe964 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -721,7 +721,7 @@ struct fwnode_handle *device_get_next_child_node(struct device *dev,
>  		return next;
>  
>  	/* When no more children in primary, continue with secondary */
> -	if (!IS_ERR_OR_NULL(fwnode->secondary))
> +	if (fwnode && !IS_ERR_OR_NULL(fwnode->secondary))
>  		next = fwnode_get_next_child_node(fwnode->secondary, child);
>  
>  	return next;