[PATCH 5.10 097/111] usb: gadget: f_fs: Fix a race condition when processing setup packets.

Greg Kroah-Hartman
2024-05-14T11:51:43Z

From: Chris Wulff <Chris.Wulff@biamp.com>

commit 0aea736ddb877b93f6d2dd8cf439840d6b4970a9 upstream.

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

--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -3403,7 +3403,7 @@ static int ffs_func_setup(struct usb_fun
__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,