Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
IronPort-SDR: 5j2gXmfIar4y/PK4X+4aMPH0oLHne63aFz8r1AihWn59PVIvIuiYdsJYaat5I7hg1rSjjyQl0T
 iVQmYhbo47DUcX8Ousg9Pr8sl7+eqmkl69PMMkL3zIR6UamJFjK+kuIwDekHG5K0uaGZPPcHah
 Oiz9p4mXVnSucZSlrPuM6CKwFhoHj7kyn73v0/bhQqbRlJFwJWfCrw6LDs4nEaxcsmNWx9HTgF
 40LzYNyWzlRrlSrA1JiP4oHNb0eYs4SKdSGbLlmq1rOVWhlHSY/uF1DICln9UrI4SVcPo38ml7
 zag=
Subject: Re: [PATCH] usb: usb251xb: fix to avoid potential NULL pointer
 dereference
To:     Aditya Pakki <pakki001@umn.edu>
CC:     <kjlu@umn.edu>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <20190318235605.11055-1-pakki001@umn.edu>
From:   Richard Leitner <richard.leitner@skidata.com>
Message-ID: <3579fc19-dde7-968b-3918-39f1cc4ee3bc@skidata.com>
Date:   Tue, 19 Mar 2019 14:11:23 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.5.1
MIME-Version: 1.0
In-Reply-To: <20190318235605.11055-1-pakki001@umn.edu>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 19/03/2019 00:56, Aditya Pakki wrote:
> of_match_device in usb251xb_probe can fail and returns a NULL pointer.
> The patch avoids a potential NULL pointer dereference in this scenario.
> 
> Signed-off-by: Aditya Pakki <pakki001@umn.edu>
> ---
>   drivers/usb/misc/usb251xb.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/misc/usb251xb.c b/drivers/usb/misc/usb251xb.c
> index 4d72b7d1d383..fe5266dc8864 100644
> --- a/drivers/usb/misc/usb251xb.c
> +++ b/drivers/usb/misc/usb251xb.c
> @@ -612,6 +612,8 @@ static int usb251xb_probe(struct usb251xb *hub)
>   							   dev);
>   	int err;
>   
> +	if (!of_id)
> +		return -ENODEV;

Hi Aditya,
thanks for finding this issue!

Nonetheless I'd prefer to change this to not return here but rather do 
something like:

	if (np && of_id) {

So we still may bring up the hub in its default config in scenarios 
without dt/of...

Any comments/objections on that?

regards;Richard.L

>   	if (np) {
>   		err = usb251xb_get_ofdata(hub,
>   					  (struct usb251xb_data *)of_id->data);
>