linux-kernel - Re: [PATCH 3/3] firmware: stratix10-svc: fix leaked of

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Date:   Wed, 17 Apr 2019 13:32:35 +0200
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Wen Yang <wen.yang99@....com.cn>, linux-kernel@...r.kernel.org
Cc:     wang.yi59@....com.cn,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Tull <atull@...nel.org>,
        Richard Gong <richard.gong@...el.com>
Subject: Re: [PATCH 3/3] firmware: stratix10-svc: fix leaked of_node
 references

On Wed, 2019-04-17 at 10:44 +0800, Wen Yang wrote:
> In stratix10_svc_init function, fw_np is obtained by calling
> of_find_node_by_name(), np is obtained by calling
> of_find_matching_node(), and the reference counts of those
> two device_nodes, fw_np and np, are increased.
> But when the function exits, only of_node_put is called on np,
> and fw_np's reference count is leaked.
> 
> Detected by coccinelle with the following warnings:
> ./drivers/firmware/stratix10-svc.c:1020:2-8: ERROR: missing of_node_put;
> acquired a node pointer with refcount incremented on line 1014, but without a
> corresponding object release within this function.
> ./drivers/firmware/stratix10-svc.c:1025:2-8: ERROR: missing of_node_put;
> acquired a node pointer with refcount incremented on line 1014, but without a
> corresponding object release within this function.
> ./drivers/firmware/stratix10-svc.c:1027:1-7: ERROR: missing of_node_put;
> acquired a node pointer with refcount incremented on line 1014, but without a
> corresponding object release within this function.
> 
> Signed-off-by: Wen Yang <wen.yang99@....com.cn>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Alan Tull <atull@...nel.org>
> Cc: Richard Gong <richard.gong@...el.com>
> Cc: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/firmware/stratix10-svc.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/firmware/stratix10-svc.c b/drivers/firmware/stratix10-
> svc.c
> index 6e65148..482a6bd 100644
> --- a/drivers/firmware/stratix10-svc.c
> +++ b/drivers/firmware/stratix10-svc.c
> @@ -1016,15 +1016,21 @@ static int __init stratix10_svc_init(void)
>  		return -ENODEV;
>  
>  	np = of_find_matching_node(fw_np, stratix10_svc_drv_match);

Sorry but this patch isn't right, of_find_matching_node() will free the
reference to fw_np internally.

> -	if (!np)
> -		return -ENODEV;
> +	if (!np) {
> +		ret = -ENODEV;
> +		goto out_put_fw_np;
> +	}
>  
>  	of_node_put(np);
>  	ret = of_platform_populate(fw_np, stratix10_svc_drv_match, NULL, NULL);
>  	if (ret)
> -		return ret;
> +		goto out_put_fw_np;

Consequently and assuming I'm not missing something, I think fw_np shouldn't be
used here as is.

Regards,
Nicolas


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