linux-kernel - [PATCH 2/2] usb: dwc2: forbid queuing request to a disabled ep

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Message-Id: <1448860888-9841-3-git-send-email-changbin.du@intel.com>
Date:	Mon, 30 Nov 2015 13:21:28 +0800
From:	changbin.du@...el.com
To:	johnyoun@...opsys.com
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Du, Changbin" <changbin.du@...el.com>
Subject: [PATCH 2/2] usb: dwc2: forbid queuing request to a disabled ep

From: "Du, Changbin" <changbin.du@...el.com>

Queue a request to disabled ep  doesn't make sense, and induce caller
make mistakes.

Here is a example for the android mtp gadget function driver. A mem
corruption can happen on below senario.
1) On disconnect, mtp driver disable its EPs,
2) During send_file_work and receive_file_work, mtp queues a request
   to ep. (The mtp driver need improve its synchronization logic!)
3) mtp_function_unbind is invoked and all mtp requests are freed.
4) when dwc2 process the request queued on step 2, will cause kernel
   NULL pointer dereference exception.

Signed-off-by: Du, Changbin <changbin.du@...el.com>
---
 drivers/usb/dwc2/gadget.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 586bbcd..4d637ab 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -786,6 +786,12 @@ static int dwc2_hsotg_ep_queue(struct usb_ep *ep, struct usb_request *req,
 		ep->name, req, req->length, req->buf, req->no_interrupt,
 		req->zero, req->short_not_ok);
 
+	if (!hs_ep->enabled) {
+		dev_warn(hs->dev, "%s: cannot queue to disabled ep\n",
+				__func__);
+		return -ESHUTDOWN;
+	}
+
 	/* Prevent new request submission when controller is suspended */
 	if (hs->lx_state == DWC2_L2) {
 		dev_dbg(hs->dev, "%s: don't submit request while suspended\n",
-- 
2.5.0

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