[PATCH 3.16 029/294] usb: renesas_usbhs: gadget: Fix NULL pointer dereference in usbhsg_ep_dequeue()

[Ben Hutchings]

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

commit c9eb29503e9655e70448bbbf3697d08a56d24854 upstream.

This patch fixes an issue that NULL pointer dereference happens when
a gadget driver calls usb_ep_dequeue() for ep0 after disconnected
a usb cable. This is because that usbhsg_try_stop() will call
usbhsg_ep_disable(&dcp->ep) when a usb cable is disconnected and
the pipe of dcp (ep0) is set to NULL.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/renesas_usbhs/mod_gadget.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/usb/renesas_usbhs/mod_gadget.c
+++ b/drivers/usb/renesas_usbhs/mod_gadget.c
@@ -126,7 +126,8 @@ static void usbhsg_queue_pop(struct usbh
 	struct usbhs_pipe *pipe = usbhsg_uep_to_pipe(uep);
 	struct device *dev = usbhsg_gpriv_to_dev(gpriv);
 
-	dev_dbg(dev, "pipe %d : queue pop\n", usbhs_pipe_number(pipe));
+	if (pipe)
+		dev_dbg(dev, "pipe %d : queue pop\n", usbhs_pipe_number(pipe));
 
 	ureq->req.status = status;
 	ureq->req.complete(&uep->ep, &ureq->req);
@@ -669,7 +670,13 @@ static int usbhsg_ep_dequeue(struct usb_
 	struct usbhsg_request *ureq = usbhsg_req_to_ureq(req);
 	struct usbhs_pipe *pipe = usbhsg_uep_to_pipe(uep);
 
-	usbhs_pkt_pop(pipe, usbhsg_ureq_to_pkt(ureq));
+	if (pipe)
+		usbhs_pkt_pop(pipe, usbhsg_ureq_to_pkt(ureq));
+
+	/*
+	 * To dequeue a request, this driver should call the usbhsg_queue_pop()
+	 * even if the pipe is NULL.
+	 */
 	usbhsg_queue_pop(uep, ureq, -ECONNRESET);
 
 	return 0;