Re: [PATCH v2] usb: gadget: f_fs: Fix a race condition when processing setup packets.

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Apr 18, 2024 at 04:45:12PM +0000, Chris Wulff wrote:
> If the USB driver passes a pointer into the TRB buffer for creq, this
> buffer can be overwritten with the status response as soon as the event
> is queued. This can make the final check return USB_GADGET_DELAYED_STATUS
> when it shouldn't. Instead use the stored wLength.
> 
> Signed-off-by: Chris Wulff <chris.wulff@biamp.com>
> ---
> v2: Added signoff
> 
>  drivers/usb/gadget/function/f_fs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
> index bffbc1dc651f..8d72acf9a760 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -3803,7 +3803,7 @@ static int ffs_func_setup(struct usb_function *f,
>  	__ffs_event_add(ffs, FUNCTIONFS_SETUP);
>  	spin_unlock_irqrestore(&ffs->ev.waitq.lock, flags);
>  
> -	return creq->wLength == 0 ? USB_GADGET_DELAYED_STATUS : 0;
> +	return ffs->ev.setup.wLength == 0 ? USB_GADGET_DELAYED_STATUS : 0;
>  }

What commit id does this fix?

And should it be backported to older kernels?

And again, please cc: the relevent maintainer/developers on your changes
so they know to read them.

thanks,

greg k-h