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Date:   Sat, 19 Jun 2021 22:13:37 -0400
From:   Alan Stern <stern@rowland.harvard.edu>
To:     Linyu Yuan <linyyuan@codeaurora.org>
Cc:     Felipe Balbi <balbi@kernel.org>,
        Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jack Pham <jackp@codeaurora.org>
Subject: Re: [PATCH v3 1/2] usb: udc: core: hide struct usb_gadget_driver to
 gadget driver
Message-ID: <20210620021337.GA361976@rowland.harvard.edu>
References: <20210619154309.52127-1-linyyuan@codeaurora.org>
 <20210619154309.52127-2-linyyuan@codeaurora.org>
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On Sat, Jun 19, 2021 at 11:43:08PM +0800, Linyu Yuan wrote:
> currently most gadget driver have a pointer to save
> struct usb_gadget_driver from upper layer,
> it allow upper layer set and unset of the pointer.
> 
> there is race that upper layer unset the pointer first,
> but gadget driver use the pointer later,
> and it cause system crash due to NULL pointer access.

This race has already been fixed in Greg's usb-next branch.  See commit 
7dc0c55e9f30 ("USB: UDC core: Add udc_async_callbacks gadget op") and 
following commits 04145a03db9d ("USB: UDC: Implement 
udc_async_callbacks in dummy-hcd") and b42e8090ba93 ("USB: UDC: 
Implement udc_async_callbacks in net2280").

You just need to write a corresponding patch implementing the 
async_callbacks op for dwc3.

Alan Stern