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

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.

Fixes: 4d644abf2569 ("usb: gadget: f_fs: Only return delayed status when len is 0")
Cc: stable <stable@kernel.org>
Signed-off-by: Chris Wulff <chris.wulff@biamp.com>
Link: https://lore.kernel.org/r/CO1PR17MB5419BD664264A558B2395E28E1112@CO1PR17MB5419.namprd17.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index aa80c2a6b8e07063ff2714c08082565c8ca20894..a057cbedf3c9b30430eeb3a8749975e58cec54da 100644 (file)
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -3811,7 +3811,7 @@ 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,