linux-kernel - Re: [PATCH] usb: cdns3: removed useless condition in cdns3_gadget_ep

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Message-ID: <20220716121456.GA238342@nchen-desktop>
Date:   Sat, 16 Jul 2022 20:14:56 +0800
From:   Peter Chen <peter.chen@...nel.org>
To:     Andrey Strachuk <strochuk@...ras.ru>
Cc:     Pawel Laszczak <pawell@...ence.com>,
        Roger Quadros <rogerq@...nel.org>,
        Aswath Govindraju <a-govindraju@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: cdns3: removed useless condition in
 cdns3_gadget_ep_dequeue()

On 22-07-11 18:10:32, Andrey Strachuk wrote:
> Comparison of 'ep' with NULL is useless since
> 'ep' is a result of container_of and cannot be NULL
> in any reasonable scenario.
> 

If ep is NULL, the container_of(NULL, struct cdns3_endpoint,
endpoint) will not cause panic, but later ep->desc will cause panic.
So we can't delete the NULL check for ep.

Peter

> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Signed-off-by: Andrey Strachuk <strochuk@...ras.ru>
> Fixes: 64b558f597d1 ("usb: cdns3: Change file names for cdns3 driver.")
> ---
>  drivers/usb/cdns3/cdns3-gadget.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
> index 5c15c48952a6..f31b389ae0b2 100644
> --- a/drivers/usb/cdns3/cdns3-gadget.c
> +++ b/drivers/usb/cdns3/cdns3-gadget.c
> @@ -2608,7 +2608,7 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep,
>  	unsigned long flags;
>  	int ret = 0;
>  
> -	if (!ep || !request || !ep->desc)
> +	if (!request || !ep->desc)
>  		return -EINVAL;
>  
>  	spin_lock_irqsave(&priv_dev->lock, flags);
> -- 
> 2.25.1
> 

-- 

Thanks,
Peter Chen