usb: gadget: f_fs: Fix a race condition when processing setup packets.

Commit Message

Chris Wulff April 16, 2024, 7:28 p.m. UTC

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.
---
 drivers/usb/gadget/function/f_fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Greg KH April 18, 2024, 2:38 p.m. UTC | #1

On Tue, Apr 16, 2024 at 07:28:27PM +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.
> ---
>  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;
>  }
>  
>  static bool ffs_func_req_match(struct usb_function *f,
> -- 
> 2.34.1
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
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If you wish to discuss this problem further, or you have questions about
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thanks,

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Patch

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;
 }
 
 static bool ffs_func_req_match(struct usb_function *f,