linux-kernel - Re: [PATCH 5.10 011/452] usb: dwc3: gadget: Move null pinter check to proper place

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Message-ID: <20220608113354.GA9333@duo.ucw.cz>
Date:   Wed, 8 Jun 2022 13:33:54 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        stable <stable@...nel.org>, Albert Wang <albertccwang@...gle.com>
Subject: Re: [PATCH 5.10 011/452] usb: dwc3: gadget: Move null pinter check
 to proper place

Hi!

> commit 3c5880745b4439ac64eccdb040e37fc1cc4c5406 upstream.
> 
> When dwc3_gadget_ep_cleanup_completed_requests() called to
> dwc3_gadget_giveback() where the dwc3 lock is released, other thread is
> able to execute. In this situation, usb_ep_disable() gets the chance to
> clear endpoint descriptor pointer which leds to the null pointer
> dereference problem. So needs to move the null pointer check to a proper
> place.

Ok, but could someone check the error handling there? There's some
cleanup at the out label, but moved code does not jump there.

Best regards,
								Pavel

> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2960,14 +2960,14 @@ static bool dwc3_gadget_endpoint_trbs_co
>  	struct dwc3		*dwc = dep->dwc;
>  	bool			no_started_trb = true;
>  
> -	if (!dep->endpoint.desc)
> -		return no_started_trb;
> -
>  	dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
>  
>  	if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)
>  		goto out;
>  
> +	if (!dep->endpoint.desc)
> +		return no_started_trb;
> +
>  	if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
>  		list_empty(&dep->started_list) &&
>  		(list_empty(&dep->pending_list) || status == -EXDEV))
> 

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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